TNF-alpha, IL-6, IFN-gamma, and IL-10 gene expression polymorphisms and the IL-4 receptor alpha-chain variant Q576R: effects on renal allograft outcome

Mycophenolate mofetil enhances the effects of tacrolimus on the inhibitory function of regulatory T cells in patients after liver transplantation via PD-1 and TIGIT receptors

OBJECTIVE

Regulatory T cells (Tregs) induce immune tolerance in patients after organ transplantation. Various immunosuppressors can affect Tregs function through different mechanisms. PD-1 and TIGIT are important receptors on Tregs surface. Here, we investigated the effects of Tacrolimus and mycophenolate mofetil (MMF) on the inhibitory function of Tregs and explored the regulatory mechanism in patients after liver transplantation.

METHODS

Thirty patients that underwent a liver transplant and 15 healthy people were enrolled. Fifteen patients received Tacrolimus only, and 15 received a combination of Tacrolimus and MMF. Tregs and effector T cells (Teffs) were isolated using magnetic beads and were mixed at different ratios of 0:1, 1:4, 1:2 and 1:1. An inhibition assay was performed by adding anti-PD-1 and anti-TIGIT when the mixture ratio was 1:1. The Tregs inhibition rate was determined and the levels of IFN-γ and TNF-α were measured.

RESULTS

As the ratios of Tregs to Teffs in the mixture increased, the Tregs inhibition rate increased and the levels of IFN-γ and TNF-α decreased. At each mixture ratio, Tacrolimus + MMF group had the highest Tregs inhibition rate compared to Tacrolimus and control group. At the specific mixture ratio of 1:1, the addition of both anti- PD-1 and anti-TIGIT led to lower Tregs inhibition rate and higher IFN-γ and TNF-α levels in all three groups as opposed to the addition of each antibody separately. Additionally, both the decrease in the Tregs inhibition rate and the increase in the IFN-γ and TNF-α levels were the most for Tacrolimus + MMF group among all cases, either adding antibodies alone or mixed.

CONCLUSION

Tacrolimus and MMF enhanced the function of Tregs by synergistically affecting PD-1 and TIGIT in liver transplant patients.

Influence of Interferon Gamma +874 T>A (rs2430561) Polymorphism on Renal Allograft Rejection: A Meta-analysis

BACKGROUND

Reported associations of the interferon gamma (IFNG) +874T/A (rs2430561) polymorphism with post-kidney transplantation allograft rejection (AR) have been inconsistent, prompting a meta-analysis to obtain more precise estimates.

METHODS

Eighteen articles (22 studies) were included in the meta-analysis. Operating on the hypothesis that IFNG rs2430561 either increases or reduces AR risk, we used a genetic model-free approach to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Subgrouping was based on ethnicity (white, Middle Eastern, black, and mixed) and rejection type (ACR: acute rejection and CHR: chronic rejection). Quality of the associative effects was assessed with sensitivity treatment and test for publication bias.

RESULTS

The overall analysis in the dominant model indicated increased risk (OR = 1.26; P^a = .02) was validated in the ACR subgroup (OR = 1.29; P^a = .01), which contrasted with the CHR subgroup, with a nonsignificant effect indicating reduced risk (OR = 0.83; P^a = .68). Only the black subgroup showed significant increased risk (OR = 2.87; P^a = .04), but the association was tenuous on account of low sample size (n = 2) and imprecise effect (95% CI, 1.07-7.73).

CONCLUSIONS

Increased risk associations (overall and ACR) of IFNG rs2430561 with AR is significant, robust, statistically powered, and lacking bias. Contrasting ACR (1.3-fold increased risk) and CHR (7% protective) effects may be clinically relevant in the genetics of renal transplantation.

Anti-CD47 monoclonal antibody therapy reduces ischemia-reperfusion injury of renal allografts in a porcine model of donation after cardiac death

We investigated whether blockade of the CD47 signaling pathway could reduce ischemia-reperfusion injury (IRI) of renal allografts donated after cardiac death (DCD) in a porcine animal model of transplantation. Renal allografts were subjected to 30 minutes of warm ischemia, 3.5 hours of cold ischemia, and then perfused with a humanized anti-CD47 monoclonal antibody (CD47mAb) in the treatment group or HTK solution in the control group (n = 4/group). The animals were euthanized five days after transplantation. At the time of reperfusion, indocyanine green-based in vivo imaging showed that CD47mAb-treated organs had greater and more uniform reperfusion. On post-transplant days 3-5, the treatment group had lower values compared to the control for creatinine and blood urea nitrogen. Histological examination of allograft tissues showed a significant decrease of acute tubular injury in the CD47mAb-treated group compared to control. Compared to the control group, CD47mAb treatment significantly decreased genes expression related to oxidative stress (sod-1, gpx-1, and txn), the inflammatory response (il-2, il-6, inf-g, and tgf-b), as well as reduced protein levels of BAX, Caspase-3, MMP2, and MMP9. These data demonstrate that CD47mAb blockade decreases IRI and subsequent tissue injury in DCD renal allografts in a large animal transplant model.

Genetic predictors of long-term graft function in kidney and pancreas transplant patients

Kidney and pancreas transplantation have helped transform the lives of people with end-stage renal failure and individuals with type 1 diabetes who have poor glycaemic control/severe secondary complications, respectively. Despite an improvement in immunosuppressive regimes, operative techniques and decreased initial rejection rates, there has been little improvement in long-term graft survival rates over the past decade. Whilst limited progress has been made in establishing clinical markers of graft function, several genetic markers of long-term graft function have been identified. These genetic markers have the potential to (i) assist in selecting marginal donor organs for transplantation, (ii) provide better understanding of the mechanisms behind graft loss enabling identification of new, or repurposing, current treatments to extend graft function and (iii) provide a window of opportunity to identify and treat individuals before graft failure has occurred. This review will discuss the different genetic variants screened for a role in predicting transplant longevity, examine their findings and limitations and introduce where the future of genetic research within the transplantation field lies.

Association Interleukin-4 and Interleukin-4 Receptor Gene Polymorphism and Acute Rejection and Graft Dysfunction After Kidney Transplantation

BACKGROUND

Cytokine genotypes have previously been studied in patients undergoing solid organ transplantation; certain polymorphisms have been implicated in the development of acute rejection (AR) and graft dysfunction (GD). Allograft outcomes determined, in part, by alloimmune responses is mainly mediated by T-cell responses, activated and driven by cytokines. Interleukin-4 (IL-4) is one such cytokine, which exerts its biological effects through binding to the IL-4 receptor (IL-4R) complex on target cells. In the present study, we investigated whether polymorphisms of the IL-4 and/or IL-4R gene were associated with susceptibility to acute AR and GD after kidney transplantation.

METHODS

We analyzed 2 single nucleotide polymorphism (SNPs) of IL-4 (rs2243250 and rs2070874) and 3 SNPs of IL-4R (rs1801275, rs2107356, and rs1805010) in 344 kidney transplant recipients. These patients included 62 of whom had developed AR and 215 of whom had GD in 1 year after kidney transplantation.

RESULTS

The AR group included 62 patients (45 men and 17 women). There was a statistically significant difference in the male-to-female ratio and the use of tacrolimus in the AR group. The GD group included 215 patients. Patients who developed GD were more likely to be older and have an underlying cause of end-stage renal disease that was unknown compared with patients who did not have GD, the cause of which was typically known. Among the SNPs examined, 1 of the SNPs in the IL-4R gene (ie, rs1801275) showed a statistical association with AR (co-dominant model, P = .061; dominant model, P = .019; and log-addictive model, P = .029). In addition, 1 of the IL-4R SNPs (ie, rs2107356) was statistically associated with GD (dominant model, P = .034). No significant difference in the IL-4 genotype was observed between the AR/GD and non-AR/non-GD subjects.

CONCLUSIONS

One IL-4R gene polymorphism (rs1801275) was associated with AR. In addition, a separate IL-4R SNP (rs2107356) was statistically associated with GD after kidney transplantation.

T-Cell Cytokines as Predictive Markers of the Risk of Allograft Rejection

Over the last decade, several biomarkers and surrogate markers have surfaced as promising predictive markers of risk of rejection in solid organ transplantation. The monitoring of these markers can help to improve graft and recipient care by personalizing immunomodulatory therapies. The complex immune system response against an implanted graft can change during long-term follow-up, and the dynamic balance between effector and regulatory T-cell populations is a crucial factor in antidonor response, risk of rejection, and immunosuppression requirements. Therefore, at any time before and after transplantation, T-effector activity, which is associated with increased production and release of proinflammatory cytokines, can be a surrogate marker of the risk of rejection and need for immunosuppression. In addition, immunosuppressive drugs may have a different effect in each individual patient. The pharmacokinetics and pharmacodynamics of these drugs show high interpatient variability, and pharmacodynamic markers, strongly associated with the specific mechanism of action, can potentially be used to measure individual susceptibility to a specific immunosuppressive agent. The monitoring of a panel of valid biomarkers can improve patient stratification and the selection of immunosuppressive drugs. After transplantation, therapy can be adjusted based on the prediction of rejection episodes (maintained alloreactivity), the prognosis of allograft damage, and the individual's response to the drugs. This review will focus on current data indicating that changes in the T-cell production of the intracellular cytokines interferon-γ and interleukin-2 could be used to predict the risk of rejection and to guide immunosuppressive therapy in transplant recipients.

Association Between Cytokines and Their Receptor Antagonist Gene Polymorphisms and Clinical Risk Factors and Acute Rejection Following Renal Transplantation

BACKGROUND Acute rejection (AR) after renal transplantation affects both patient and graft survival. There is growing evidence of the genetic association between cytokine or its receptor antagonist and AR in solid organ transplantation. The objectives of this study were to investigate the role of recipient TNF β, IL-10, IL-1β, and IL-1 receptor antagonist (ra) gene polymorphism, as well as traditional clinical variables such as panel-reactive antibody (PRA) levels, donor type, and HLA mismatches in AR following renal transplantation. MATERIAL AND METHODS TNF β (+252A/G), IL-10 (-592A/C), IL-1β (-511C/T) and IL-1ra (86 bp VNTR) gene polymorphisms were determined in 195 renal allograft recipients with and without AR, using PCR. Both these genotypic variants and clinical risk factors were investigated for correlation with AR within the first year after renal transplantation. RESULTS Patients with increased pre-transplant PRA levels (P<0.001) and donor type (P=0.012) were prone to the development of AR. After adjusting for all variables of P<0.2, a PRA level >10% (OR=4.515, 95% confidence intervals=1.738-11.727, P=0.002) and the receipt of a graft from a donation after cardiac death (DCD) donor (OR=2.437, 95% confidence intervals=1.047-5.673, P=0.039) remained significantly associated with AR in a multivariate logistic regression analysis. No correlation could be found between recipients with an episode and absence of acute rejection and the gene polymorphisms of these cytokines investigated in the present study. CONCLUSIONS This study shows that the presence of increased pre-transplant levels of PRA and the receipt of a graft from DCD donor other than cytokine gene polymorphisms are significant risk factors for AR in renal transplantation. To reduce the occurrence of AR, clinicians should take necessary measures to lower the PRA levels and pay more attention to patients who received a graft from a DCD donor.

The Polymorphism -308G/A of Tumor Necrosis Factor-α Gene Modulates the Effect of Immunosuppressive Treatment in First Kidney Transplant Subjects Who Suffer an Acute Rejection

The -308G/A SNP of tumor necrosis factor-alpha (TNF-α) gene affects TNF-α production. As its impact on transplant outcome remains open to debate, we decided to genotype it in a cohort of transplant subjects. A retrospective analysis of 439 first kidney recipients randomly divided into two subgroups (discovery and validation cohorts) was performed to identify the best predictors of acute rejection (AR). The effect on transplant outcome was analyzed by an adjusted logistic regression model. Carriers of the A allele, associated with elevated TNF-α production, presented a higher risk of AR (OR = 2.78; 95% CI = 1.40-5.51). Logistic regression analyses for AR showed an interaction between the polymorphism and treatment with thymoglobulin (p-interaction = 0.03). In recipients who did not receive thymoglobulin, carriers of A allele had higher risk of AR (OR = 4.05; 95% CI = 1.76-9.28). Moreover, carriers of A allele not treated with thymoglobulin presented higher risk of AR than those who received thymoglobulin (OR = 13.74; 95% CI = 1.59-118.7). The AUC of the model in the discovery cohort was 0.70 and in the validation cohort was 0.69. Our findings indicate that the -308G/A TNF-α polymorphism is associated with AR risk and it modulates the effectiveness of thymoglobulin treatment. This pharmacogenetic effect lets us propose this SNP as a useful predictor biomarker to tailor immunosuppressive regimens.

Interleukin-10-1082 G/a polymorphism and acute renal graft rejection: a meta-analysis

OBJECTIVE

The aim of this study was to investigate the association between interleukin (IL)-10-1082 (G/A) promoter polymorphism and acute rejection (AR) in renal transplant recipients.

METHODS

We searched MEDLINE, EMBASE, Web of Science, and Cochrane Central Register from the inception to March 2015 for relevant studies. Data concerning publication information, population characteristics, and transplant information were extracted. Odds ratios (ORs) was calculated for the association between IL-10-1082 GG genotype (or IL-10-1082 G allele) and AR risk.

RESULTS

This meta-analysis included 22 case-control studies including 2779 cases of renal transplant recipients. The pooled estimate showed that the IL-10-1082 GG genotype was not significantly associated with AR risk (ORrandom=1.07, 95% CI 0.80-1.43, p = 0.64). Similarly, the pooled estimate showed that the IL-10-1082 G allele was not significantly associated with AR risk (ORfixed=1.02, 95% CI 0.90-1.16, p = 0.74). None of subgroup analyses yielded significant results in the association between IL-10-1082 GG genotype (or IL-10-1082 G allele) and AR risk. Meta-regression confirmed that there was no significant correlation between the pre-selected trial characteristics and our study results.

CONCLUSIONS

This meta-analysis suggests that IL-10-1082 G/A polymorphism is not significantly associated with AR risk in renal transplant recipients.

Association of interferon gamma gene polymorphisms with BK virus infection among Hispanic renal allograft recipients

BACKGROUND

BK virus nephropathy is one of the most common viral infections that affect up to 10% of renal transplant recipients (RTRs), causing allograft dysfunction and graft loss. Interferon-gamma (IFN-γ) gene polymorphisms have been associated with parvovirus B19, hepatitis C virus, HIV-1/AIDS infection, cytomegalovirus viremia, and disease. IFN-γ is known to have potent inhibitory effects on BK virus gene expression, both at the level of transcription and translation.

METHODS

It was investigated whether IFN-γ polymorphisms are associated with BKV infection. Genotyping of four single-nucleotide polymorphisms located in the IFN-γ gene were performed on DNA collected from a total of 251 RTRs (71 RTRs with BKV infection and 180 without BKV infection).

RESULTS

Analysis of the results showed that IFN-γ (rs12369470) CC genotype was significantly associated with susceptibility to BKV infection (OR: 2.9, 95% CI: 1.29-6.44, P=0.007) while the IFN-γ +874 (rs2435061) TT and (rs2406918) CC genotypes appear to be markers for protection against BKV infection (OR: 0.29, 95% CI: 0.1-0.83, P=0.01 for rs245061; OR: 0.61, 95% CI: 0.4-0.94, P=0.02 for rs24069718). A haplotype analysis using the combination of rs2435061-rs2406918-rs2870953 showed that the A-G-T haplotype was associated with a significantly reduced risk for BKV infection (OR: 0.43, 95% CI: 0.25-0.73, P=0.001).

CONCLUSION

Polymorphisms in the IFN-γ gene may confer certain protection or predisposition for BKV infection.

Cytokines as biomarkers in rheumatoid arthritis

RA is a complex disease that develops as a series of events often referred to as disease continuum. RA would benefit from novel biomarker development for diagnosis where new biomarkers are still needed (even if progresses have been made with the inclusion of ACPA into the ACR/EULAR 2010 diagnostic criteria) and for prognostic notably in at risk of evolution patients with autoantibody-positive arthralgia. Risk biomarkers for rapid evolution or cardiovascular complications are also highly desirable. Monitoring biomarkers would be useful in predicting relapse. Finally, predictive biomarkers for therapy outcome would allow tailoring therapy to the individual. Increasing numbers of cytokines have been involved in RA pathology. Many have the potential as biomarkers in RA especially as their clinical utility is already established in other diseases and could be easily transferable to rheumatology. We will review the current knowledge's relation to cytokine used as biomarker in RA. However, given the complexity and heterogeneous nature of RA, it is unlikely that a single cytokine may provide sufficient discrimination; therefore multiple biomarker signatures may represent more realistic approach for the future of personalised medicine in RA.

Association between interferon gamma +874 T>A polymorphism and acute renal allograft rejection: evidence from published studies

Interferon gamma is involved in the acute rejection (AR) episodes of transplant recipients. However, results from published studies on the association of interferon gamma (IFNG) +874 T>A (rs2430561) polymorphism with AR of renal allograft are conflicting. To investigate the association between IFNG +874 T>A polymorphism with AR after renal transplantation, relevant studies were selected from PUBMED, EMBASE, Wanfang database and China National Knowledge Infrastructure until March 1st 2013. According the predesigned selection criteria, a total of 525 AR cases and 1,126 non-AR cases from 13 case-control studies were included to identify the strength of association with odds ratio (OR) and 95 % confidence intervals (95 % CI). Overall, a significant correlation between IFNG +874 T>A polymorphism and susceptibility to AR was detected (T allele vs. A allele: OR = 1.19, 95 % CI 1.02-1.38; TT/AT vs. AA: OR = 1.36, 95 % CI 1.07-1.73; TT vs. AA: OR = 1.42, 95 % CI 1.05-1.93; AT vs. AA: OR = 1.30, 95 % CI 1.01-1.68). In addition, ethnicity subgroup analysis revealed that high produce genotype (TT/AT) was associated with an increased risk of AR for Caucasians (TT/AT vs. AA: OR = 1.56, 95 % CI 1.14-2.12; TT vs. AA: OR = 1.64, 95 % CI 1.18-2.26). Furthermore, donor source subgroup analysis observed an increased risk for patients undergoing cadaveric kidney transplantation (TT/AT vs. AA: OR = 1.90, 95 % CI 1.12-3.24; TA vs. AA: OR = 2.16, 95 % CI 1.24-3.74). In conclusion, this meta-analysis suggested that IFNG +874 T>A polymorphism was associated with AR of renal transplant recipients, especially among Caucasians and those receiving cadaveric renal allograft. Additional well-designed studies with large sample size are warranted to validate our conclusion.

Cytokine gene polymorphisms: methods of detection and biological significance

In recent years, several functional polymorphisms, particularly, SNPs have been identified in cytokines and their receptor genes that regulate levels of cytokine expression. These have been implicated as immune prognostic markers in diseases, including differential response to therapy and as biomarkers of graft outcome following organ and stem cell transplantation. Population distribution of cytokine gene polymorphisms (CGPs) reveals significant variations in allele frequencies in different ethnic groups and this might explain, to some extent, the observed differences in SNP associations with various diseases and immune-pathologies. A number of molecular methods are available for defining CGPs. These include PCR-SSP, AFLP, Taqman probe assays as well as sequencing based typing. Of these, the PCR-based sequence-specific primer based test is the most widely accepted technique. This chapter describes steps involved in this procedure along with sources for procuring essential reagents. An important aspect of CGP analyses is the correct interpretation of results particularly determination of their multilocus haplotypes.

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.

Association between IL-6 -174G/C polymorphism and acute rejection of renal allograft: evidence from a meta-analysis

BACKGROUND

Results from published studies on the association of donor or recipient IL-6 -174G/C (rs1800795) polymorphism with acute rejection (AR) of renal allograft are conflicting. We performed a meta-analysis to estimate the possible association.

METHODS

Studies were identified by searching PUBMED and EMBASE until July 1, 2011. Meta-analysis was performed in a fixed/random effects model using Revman 5.0.25 and STATA10.0.

RESULTS

Seven studies addressing the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute rejection of renal allograft were identified. Pooled OR based on 341 cases (whose recipient developed acute rejection) and 702 controls (whose recipient did not develop acute rejection) was 0.59 (95% CI, 0.26-1.33; p=0.20), with a strong between-study heterogeneity. No association was observed in the subgroup analysis based on ethnicity. 13 studies evaluating the association between recipient IL-6 -174G/C polymorphism and acute rejection were identified. Pooled OR based on 451 cases (patients did not develop acute rejection) and 848 controls was 1.00 (95% CI=0.72-1.37; p=0.98), with a weak between-study heterogeneity.

CONCLUSIONS

Donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism had a tendency of decreased risk for acute rejection, although it was not statistically significant. Recipient high producer genotype was not associated with acute rejection of renal allograft. Additional well designed studies with larger sample size are needed to support our findings, especially for the association between donor high producer genotype (G/G and G/C) of IL-6 -174G/C polymorphism and acute renal allograft rejection.

Elevated expression levels of ANXA11, integrins β3 and α3, and TNF-α contribute to a candidate proteomic signature in urine for kidney allograft rejection

PURPOSE

Kidney transplantation is the treatment of choice for end stage renal disease, with long-term allograft loss being the major obstacle, and for which potential treatments are based on a histological diagnosis. The problem is that markers for predicting graft rejection are limited in number, are invasive, and are quite non-specific. We have hypothesized that protein biomarkers might be discovered in the urine of patients when acute or chronic rejection might be occurring.

EXPERIMENTAL DESIGN

We have established a workflow in which initial screening for candidate biomarkers is first performed using urine samples on large-scale antibody microarrays. This approach generated several dozen candidates. The next step is to qualify some of the strongest signals using the high-throughput Reverse Capture Protein Microarray platform.

RESULTS

Four top candidates including ANXA11, Integrin α3, Integrin β3 and TNF-α, initially identified by the antibody microarray platform, were all qualified using Reverse Capture Protein Microarrays. We also used receiver operating condition (ROC) curves to independently quantify the specificity and sensitivity of these four analytes.

CONCLUSIONS AND CLINICAL RELEVANCE

The present data suggest that these novel four analytes in the urine, together or independently, may contribute to a robust and quantitative urine proteomic signature for diagnosing acute or chronic rejection of renal allografts.

A study of the impact of cytokine gene polymorphism in acute rejection of renal transplant recipients

Acute rejection is a common phenomenon in transplantation. Inflammatory and anti-inflammatory mediators affect the graft microenvironment. Th1 responses cause acute rejection while Th2 immune responses help the survival of the graft. In this study, we evaluated gene polymorphisms of IL-6 G-174C, TGF-β T+869C, IL-4 C-590T, and IFN-γ T+874A cytokines in renal transplant patients. ARMS-PCR method was used to characterize IL-6 G-174C (rs76144090), TGF-β T+869C (rs1800471), and IFN-γ T+874A (rs2430561) polymorphisms and PCR-RFLP, for characterization of IL-4 C-590T (rs2243250) in 100 renal transplant patients. Acute rejection episodes were diagnosed according to the standard criteria. Analysis of the results showed that IL-6-174 GG genotype (P=0.018, OR=3.023, 95% CI=1.183-7.726) and IL-6-174G allele (P=0.046, OR=2.114, 95% CI=1.005-4.447) were more frequent, but IL-6-174GC genotype was less frequent in acute rejection of kidney transplantation in comparison with control group (P=0.024, OR=0.302, 95% CI=0.103-0.883). IFN-γ+874 T allele was associated with a higher risk of acute rejection (P=0.019, OR=2.088, 95% CI=1.124-3.880) while IFN-γ+874 AA genotype was associated with a lower risk of rejection (P=0.023, OR=0.318, 95% CI=0.115-0.875). Frequencies of TGF-β T+869C and IL-4 C-590T were not significantly different (P>0.05). Consequently, our results show that IL-6 G-174C and IFN-γ T+874A gene polymorphisms have predictive values for acute rejection after renal transplantation in Iranian patients.

Monitoring cytokine profiles during immunotherapy

Measuring cytokine production is an integral part of measuring immune response during immunotherapy. Current technologies allow the simultaneous quantification of multiple cytokines in a variety of tissues. Patterns of cytokine response can be referred to as cytokine profiles. This article discusses the experimental design and data analysis of a number of studies that examined cytokine profiles in humans. We highlight potential sources of variability, both due to assay nuances and the diversity of human populations. We present strategies for analyzing data, emphasizing both multidimensional analysis and the value of treating each donor as his or her own control.

Graft inflammation and histologic indicators of kidney chronic allograft failure: low-expressing interleukin-10 genotypes cannot be ignored

BACKGROUND

Infiltration of inflammatory cells into the renal allograft interstitium is the biologic hallmark of alloimmune responses that leads to tubulointerstitial injury and subsequent interstitial fibrosis and chronic allograft failure. The proliferation, stimulation, and infiltration of these inflammatory cells are governed by various proinflammatory and regulatory cytokines. We assessed whether the differences in the genes encoding cytokines (producing low, moderate, or high expression profiles) may affect the infiltration of inflammatory cells into the renal allograft and the histologic changes characteristics of chronic allograft failure.

METHODS

A total of 218 kidney transplant recipients were genotyped for 15 single-nucleotide polymorphisms located in the gene promoter or exonic regions of 10 different cytokines or their receptors. Six- to 12-month posttransplant surveillance biopsies were scored using 11 individual histologic parameters and the combined grade of interstitial fibrosis and tubular atrophy (IF/TA). B-cell, T-cell, and macrophage infiltrates were quantified by immunostaining.

RESULTS

The low-expressing interleukin (IL)-10 gene promoter genotypes were found significantly associated with high IF/TA grade (IL-10 -819 TT; P=0.035; odds ratio=3.27; 95% confidence interval 1.1-9.8). At individual histologic indices, recipients carrying low-expressing IL-10 genotypes showed 2.5-fold higher scores for interstitial fibrosis, inflammation, and tubular atrophy. High infiltration of T cells and macrophages but not B cells into the renal allograft interstitium was found strongly associated with the carriage of low-expressing IL-10 genotypes.

CONCLUSIONS

The results suggest that renal transplant recipients genetically predisposed to low expression of the regulatory cytokine IL-10 are more susceptible to high grades of IF/TA scores, graft inflammation, and high influx of inflammatory cells into the graft interstitium.

Monitoring the operationally tolerant liver allograft recipient

PURPOSE OF REVIEW

A fundamental goal in transplantation is the establishment of allograft function without ongoing immunosuppression. Robust allograft tolerance has been established in experimental transplantation models, whereas clinical operational tolerance has been described most frequently following human liver transplantation.

RECENT FINDINGS

Clinical assessment of tolerance has been limited to laboratory evaluation of organ function. Additional tools include graft monitoring through biopsy and blood sampling for biomarker analysis. Current biomarkers under assessment in recent years include dendritic cell subsets, regulatory T cells, antidonor antibodies, and gene polymorphisms. Emerging microarray analysis that is being prospectively validated will also be reviewed. A further tool in the characterization of the tolerant patient will be the accurate enrollment of such patients into a multicenter registry that will prospectively follow the natural history of the patient withdrawn from immunosuppression and help facilitate the entry of interested patients to mechanistic and immune monitoring trials. The International Solid Organ Transplant Tolerance Registry (www.transplant-tolerance.org) will be briefly described.

SUMMARY

Effective biomarker characterization of the operationally tolerant liver allograft recipient would allow earlier, well tolerated, prospective drug withdrawal with the goal of extending the potential benefits of drug minimization to an increasing number of patients in a more predictable fashion.

HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

BACKGROUND

The HLA-B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients.

METHODS

From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non-glomerular diseases. Death-censored graft loss according to the HLA-B8, DR3 haplotype was calculated with Kaplan-Meier analysis and Cox-regression model was used to correct for various risk factors.

RESULTS

The frequency of the HLA-B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten-year graft survival was identical in the control group with and without the HLA-B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA-B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA-B8, DR3 haplotype and independent of well-known risk factors.

CONCLUSIONS

We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.

Immunoregulatory role of TNFalpha in inflammatory kidney diseases

Tumor necrosis factor alpha (TNFalpha), a pleiotropic cytokine, plays important inflammatory roles in renal diseases such as lupus nephritis, anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis and renal allograft rejection. However, TNFalpha also plays critical immunoregulatory roles that are required to maintain immune homeostasis. These complex biological functions of TNFalpha are orchestrated by its two receptors, TNFR1 and TNFR2. For example, TNFR2 promotes leukocyte infiltration and tissue injury in an animal model of immune complex-mediated glomerulonephritis. On the other hand, TNFR1 plays an immunoregulatory function in a murine lupus model with a deficiency in this receptor that leads to more severe autoimmune symptoms. In humans, proinflammatory and immunoregulatory roles for TNFalpha are strikingly illustrated in patients on anti-TNFalpha medications: These treatments are greatly beneficial in certain inflammatory diseases such as rheumatoid arthritis but, on the other hand, are also associated with the induction of autoimmune lupus-like syndromes and enhanced autoimmunity in multiple sclerosis patients. The indication for anti-TNFalpha treatments in renal inflammatory diseases is still under discussion. Ongoing clinical trials may help to clarify the potential benefit of such treatments in lupus nephritis and ANCA-associated glomerulonephritis. Overall, the complex biology of TNFalpha is not fully understood. A greater understanding of the function of its receptors may provide a framework to understand its contrasting proinflammatory and immunoregulatory functions. This may lead the development of new, more specific anti-inflammatory drugs.

The impact of immune gene polymorphisms in kidney and liver transplantation

Since the completion of the Human Genome Project, it has become clear that genetic variation exists among individuals that can affect functional gene expression. This finding raises the possibility that differences in genetic phenotypes may account for the interindividual responses seen in the context of the alloimmune response. This review highlights studies examining the relative role of immunologic gene polymorphism in the context of renal and liver transplant outcomes (eg, acute rejection and graft survival). Furthermore, it examines the limitations and pitfalls in the study designs and concludes with the potential of single nucleotide polymorphism analysis in the future care of transplant recipients.

Genetic prediction of renal transplant outcome

PURPOSE OF REVIEW

In the present study, we reviewed recent publications regarding potential genetic predictors of transplant outcome, including acute rejection, metabolism of immunosuppressive medications, long-term transplant outcome, and posttransplant complications.

RECENT FINDINGS

Recent studies are based on the candidate gene analysis; specifically, cytokine genes and innate immune response molecules present popular targets for studies of acute rejection and long-term outcome. Pharmacogenomic studies are mostly focused on the genes of drug targets or the corresponding enzymes metabolizing the drug. Posttransplant complications (i.e. infections, diabetes, and malignancies) are associated with a variety of genes of different pathways. Most of the studies are based on just recipient, but not donor, genotype analysis. Positive results are balanced by reports of no association when evaluating the same genetic polymorphisms. Some of the reports might be affected by insufficient study design, including small sample size, lack of adjustment for potential confounders, and multiple comparisons.

SUMMARY

The field remains controversial because of differences in populations, study design, and statistical methods. Studies are based on candidate gene analysis; however, genome-wide association studies are lacking. Future research should be directed at better designed studies, larger sample size, evaluating both recipients and donors, and implementation of genome-wide association studies.

Genetic polymorphisms and the fate of the transplanted organ

There has been an abundance of publications describing genetic variability in molecules affecting innate and adaptive immunity, pharmacogenetics, and other nonimmunological factors like the renin-angiotensin aldosterone system, coagulation, and fibrosis markers. Studies indicated some associations between polymorphisms in these candidate genes with outcomes in organ transplantation and underlined a potential role of genetic variability in transplantation. To be clinically applicable, large prospective studies must be performed to better define the potential benefits of genotyping on these genetic markers and clinical outcomes. The purposes of this review are to summarize recent data describing associations of polymorphisms in both immunological and nonimmunological molecules with transplant outcomes, with a particular emphasis on renal transplantation, and discuss limitations and clinical implications.

IL2 and TNFA gene polymorphisms and the risk of graft-versus-host disease after allogeneic haematopoietic stem cell transplantation

This study aimed to analyse the association of gene polymorphisms with the outcome of allogeneic haematopoietic stem cell transplantation. We studied 122 donor/recipient pairs who received HLA-identical transplants from siblings at the Universidade Estadual de Campinas, Brazil, between June 1996 and June 2006. Donor/recipient alleles for TNFA-238 and IL2-330/+166 single-nucleotide polymorphisms (SNP) were analysed by PCR-SSP. No association was observed between the risk of acute graft-versus-host disease (GVHD) and these SNP. However, our findings suggest that the polymorphism of promoter gene TNFA-238GA is associated with the occurrence and severity of chronic GVHD. The probability of chronic GVHD in patients with GA genotype at position -238 of TNFA gene is 91.7% in contrast to 59.4% in patients with GG genotype (P = 0.038). In patients with donor GA genotype the probability of chronic GVHD is 90.8%, and 57.9% in patients with donor GG genotype (P = 0.038). The probability of extensive chronic GVHD in patients with TNFA-238GA is 91.7% compared with 46.3% in patients with TNFA-238GG (P = 0.0046). In patients with donor GA genotype at position -238 of the TNFA gene, it is 81.7%, compared with 44.5% in patients with donor GG genotype (P = 0.016). However, further studies with more patients are required to identify cytokine gene polymorphisms and their association with transplant-related complication in Brazil, particularly due to ethnic background, the relatively low power of detection of genetic markers of this study, and the complexity of the MHC region.

Influence of cytokine genes polymorphisms on long-term outcome in renal transplantation

BACKGROUND

Recently, polymorphisms of cytokine genes have been associated with modified gene expression and increased cytokine production. We evaluated the influence of interleukin-10 (IL-10) gene G-1082A, tumour necrosis factor alpha (TNFalpha) gene G-308A and IL-6 gene G-174C polymorphisms on the rejection rate, renal function and long-term outcome in renal transplantation.

PATIENTS AND METHODS

We studied n = 224 consecutive patients, who underwent renal transplantation at our centre from 1998 to 2001 (cadaveric: n = 175, living related: n = 49) followed up for 4.9 +/- 2.0 yr and n = 100 healthy volunteers. IL-10 gene G-1082A, TNFalpha gene G-308A and IL-6 gene G-174C polymorphisms were determined by polymerase chain reaction (PCR) amplification.

RESULTS

The genotype distribution of the investigated polymorphisms was similar in patients and controls (ns). The age of donor and the recipient, the number of HLA mismatches and cold and warm ischemic time did not differ among patients with different genotypes (ns). No association between cytokine polymorphisms and the incidence of acute rejection episodes was detected (ns). The cytokine genotypes did not correlate with serum creatinine or creatinine clearance at any time during follow up (ns). Furthermore, there was no significant difference in the genotype frequencies among patients experiencing graft failure (ns). Patients with different cytokine gene polymorphisms showed similar outcomes in the Kaplan-Meier analysis of graft survival (ns). Finally, cytokine polymorphisms had no influence on the acute rejection rate or graft outcome also in the subgroup of HLA-DR mismatched grafts (ns).

CONCLUSION

Our results suggest that IL-10 gene G-1082A, TNFalpha gene G-308A and IL-6 gene G-174C polymorphisms are no major risk factors in renal transplantation.

Anti-inflammatory effects of alphav integrin antagonism in acute kidney allograft rejection

Integrin-mediated cell adhesion and signaling is essential to vascular development and inflammatory processes. Elevated expression of integrin alpha(v)beta(3) has been detected in ischemia-reperfusion injury and rejecting heart allografts. We thus hypothesized that the inhibition of alpha(v)-associated integrins may have potent anti-inflammatory effects in acute kidney allograft rejection. We studied the effects of a peptidomimetic antagonist of alpha(v) integrins in two rat models of renal allotransplantation, differing in degree of major histocompatibility complex mismatch. Integrin alpha(v)beta(3) was up-regulated in rejecting renal allografts. Integrin antagonist reduced the histological signs of acute rejection, the intensity of the mononuclear cell infiltration, and cell proliferation in the grafted kidneys. This could be correlated to a reduced leukocyte-endothelial interaction and an improved peritubular microcirculation observed by intravital microscopy. In vitro under laminar flow conditions, the arrest of monocytes to interleukin-1beta-activated endothelium was decreased. Furthermore, in co-culture models the proliferation and transmigration of monocytes/macrophages, endothelium, and fibroblasts induced by renal tubular epithelia was efficiently inhibited by alpha(v) integrin antagonism. These data reveal an important role of this integrin subclass in leukocyte recruitment and development and maintenance of acute rejection; blockade of alpha(v) integrins may provide a new therapeutic strategy to attenuate acute allograft rejection.

Functions of TNF and its receptors in renal disease: distinct roles in inflammatory tissue injury and immune regulation

Tumor necrosis factor (TNF) alpha is a potent proinflammatory cytokine and important mediator of inflammatory tissue damage. In addition, it has important immune-regulatory functions. Many experimental studies and clinical observations support a role for TNF in the pathogenesis of acute and chronic renal disease. However, given its dual functions in inflammation and immune regulation, TNF may mediate both proinflammatory as well as immunosuppressive effects, particularly in chronic kidney diseases and systemic autoimmunity. Blockade of TNF in human rheumatoid arthritis or Crohn's disease led to the development of autoantibodies, lupus-like syndrome, and glomerulonephritis in some patients. These data raise concern about using TNF-blocking therapies in renal disease because the kidney may be especially vulnerable to the manifestation of autoimmune processes. Interestingly, recent experimental evidence suggests distinct roles for the 2 TNF receptors in mediating local inflammatory injury in the kidney and systemic immune-regulatory functions. In this review the biologic properties of TNF and its receptors, TNF receptors 1 and 2, relevant to kidney disease are summarized followed by a review of the available experimental and clinical data on the pathogenic role of the TNF system in nonimmune and immune renal diseases. Experimental evidence also is reviewed that supports a rationale for specifically blocking TNF receptor 2 versus anti-TNF therapies in some nephropathies, including immune complex-mediated glomerulonephritis.

Cisplatin increases TNF-alpha mRNA stability in kidney proximal tubule cells

Cisplatin induces acute renal injury in part by increasing the production of TNF-alpha. However, the mechanism by which cisplatin increases renal TNF-alpha expression is not known. The transcription, translation, and stability of TNF-alpha mRNA are sites of regulation of TNF-alpha production. This study investigated the effects of cisplatin on TNF-alpha mRNA stability and the role of MAP kinases in this process in cultured renal proximal tubule cells. Cisplatin increased the expression of TNF-alpha mRNA by proximal tubule cells in a time- and dose-dependent manner, as well as activated p42/44 ERK kinase, p38 MAP kinase, and JNK in a dose-dependent manner. The inhibition of these pathways reduced TNF-alpha expression significantly. Cisplatin also increased the stability of TNF-alpha mRNA, but this effect was not mediated by MAP kinases and did not require the synthesis of a new protein. The treatment of cells with cisplatin induced the formation of complexes of cytosolic proteins and the AU-rich region of the TNF-alpha 3'UTR. These results are consistent with the view that cisplatin increases TNF-alpha mRNA stability in a MAP kinase-independent manner. The stabilization of TNF-alpha mRNA by cisplatin may involve the binding of certain proteins to AU-rich regions in the 3'UTR.

The G-308A promoter variant of the tumor necrosis factor-alpha gene is associated with migraine without aura

Migraine is considered to be a polygenic multifactorial disease with various environmental and genetic etiologies. Tumor necrosis factor-alpha (TNF-alpha), a potent immunomodulator and pro-inflammatory cytokine, has been implicated in many pathological processes in brain. The hypothesis of this study was that migraine without aura (MWA) might be associated with TNF-alpha (-308) polymorphism, resulting in increased TNF-alpha production. Genotyping was performed on DNA extracted from peripheral leukocytes by PCR-SSP method in 221 patients with WMA and 183 healthy control subjects from Iranian population. The results showed that the frequency of -308 A variant allele was higher in MWA than in the control group (40.6% versus 22.3%, OR 3.73, 95% CI 2.4-5.82, p<0.0001). TNF-alpha GA heterozygous genotype, high producer, was significantly more prevalent in patients with MWA than controls (74% versus 44.7%, p<0.0001) whilst the low producer GG homozygous genotype was less frequent in patients compared with controls (22.4% versus 55.3%, p<0.0001). The logistic regression analysis showed a significant association for TNF-alpha (-308A) female allele carriers with MWA at reproductive ages (OR 2.56; 95% CI, 1.57-4.16, p<0.0001) when compared with their matched control subjects. In conclusion, this study demonstrates an association of tumor necrosis factor-alpha (-308A) carriage with MWA, suggesting that carrying a high responder TNF-alpha-308A allele may be a genetic factor in increasing the susceptibility to develop MWA.

Antagonizing reactive oxygen by treatment with a manganese (III) metalloporphyrin-based superoxide dismutase mimetic in cardiac transplants

OBJECTIVE

Oxidative stress might be an important factor contributing to injury during alloimmune activation. Herein, we evaluated the efficacy of a superoxide dismutase mimetic, manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTmPyP), on cytokine gene expression and apoptotic signaling in a rat model of cardiac transplantation.

METHODS

Lewis-->Lewis (isografts) or Wistar-Furth-->Lewis (allografts) heterotopic rat transplants without and with treatment with MnTmPyP were used. Reactive oxygen formation was determined on the basis of dihydroethidine fluorescence and lucigenin-enhanced chemiluminescence. In situ graft function was determined by means of sonomicrometry. Inflammatory cytokine, proapoptotic, and antiapoptotic gene expression at either postoperative day 4 (early rejection) or postoperative day 6 (late rejection) was determined by means of reverse transcriptase polymerase chain reaction.

RESULTS

An increased production of reactive oxygen in allografts was inhibited to isograft control levels by MnTmPyP. MnTmPyP restored either the percentage of fractional shortening, the distended diastolic and systolic myocardial segment lengths, or both in allografts. Of the increases in cytokine and proapoptotic gene expression in allografts, only interleukin 6 was decreased by MnTmPyP. MnTmPyP inhibited antiapoptotic gene expression (Bcl-2 and Bcl-xL) during early rejection but restored expression at later stages. The increase in activated caspase-3 levels in allografts was inhibited by MnTmPyP.

CONCLUSIONS

The mechanism of the beneficial effect of MnTmPyP on graft function appear related, in part, to scavenging O2*- and by decreasing apoptotic signaling rather than an effect on inflammatory cytokine gene expression.

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.

Relationship between cytokine gene polymorphisms and graft-versus-host disease after allogeneic stem cell transplantation in a Brazilian population

Graft-versus-host disease (GVHD) is the major complication of allogeneic hematopoietic stem cell transplantation (HSCT), and cytokines are recognized as important mediators of GVHD. Polymorphisms in the regulatory regions of several cytokine genes have been associated with a number of immune diseases as well as organ transplant complications. In this study we have investigated the role of tumor necrosis factor-alpha(-308), interleukin (IL)-6(-174), IL-10(-1082, -819, -592), Interferon-gamma(-874), and transforming growth factor-beta1(+869, +915) polymorphisms on HSCT outcome. Donor/recipient genotypes were analyzed by polymerase chain reaction with sequence specific primers (PCR-SSP). Although we have found a small number of low IL-6, a polymorphism at position -174 of the recipient and donor IL-6 gene was associated with the increased incidence of chronic GVHD. Therefore, this study emphasizes the probable potential role of genetic variability of donor and recipient in determining outcome after transplantation.

Predictive Factors in Chronic Allograft Nephropathy

Chronic allograft nephropathy (CAN) is characterized by progressive renal dysfunction leading in many cases to graft loss. The pathogenesis of CAN involves both immune and nonimmune factors. Concerning immune factors, one of the most remarkable predictors of CAN is acute rejection, which is associated with a worse prognosis if there are multiple episodes or when late onset occurs. Delayed graft function is also a major risk factor for CAN because of a correlation between late restoration of renal function after transplantation and long-term decreased graft survival. High creatinine levels at 6 months and 1 year after transplantation, proteinuria, viral infections, and cardiovascular risk factors are additional significant parameters for the development of CAN. Recent findings suggest that a high renal segmental arterial resistance index measured by Doppler ultrasonography in intrarenal vessels is associated with poor allograft function. Moreover, the study of patient genetic profile represents a new approach to identify predictive factors for CAN.

TNF-alpha, TGF-beta, IL-10, IL-6, and INF-gamma alleles among African Americans and Cuban Americans. Report of the ASHI Minority Workshops: Part IV

Point mutations or single nucleotide substitutions in the regulatory regions of cytokine genes may affect levels of cytokine expression and have been associated with acute and chronic rejection in organ transplantation, severity of graft-versus-host disease in hematopoietic stem cell transplants, and predisposition to autoimmune disorders. Because these cytokine variants have been studied primarily among Caucasians, we defined the alleles and frequencies of five cytokines among 691 unrelated, adult African Americans and 296 Cuban Americans in the American Society for Histocompatibility/National Institutes of Health Minority HLA Workshops. The genotypes of all cytokines, except for transforming growth factor (TGF)-beta among African Americans, were found to be in Hardy-Weinberg's equilibrium. Genotype frequencies among African American and Cuban American participants were compared with those of 75 North American Caucasian bone marrow donors and with published frequencies. Significant differences were observed in all comparisons except between Cuban and Caucasian Americans for alleles of interferon (IFN)-gamma, interleukin (IL)-6, and IL-10. The most notable differences were in genotype frequencies of African Americans compared with those of the two other populations. The frequency of the IFN-gamma genotype A/A, which is associated with low expression, was significantly higher in African Americans than in Caucasian or Cuban Americans (0.66 vs 0.37 and 0.26, respectively; p < 0.0001 for both comparisons). The high-expression G/G genotype for IL-6 was more than twice as prevalent among African Americans as among Caucasians and 1.5 times more frequent than among Cuban Americans (respective frequencies: 0.85 vs 0.38 and 0.49; p < 0.0001 for both comparisons). In African Americans, the frequency of the high-expression genotype for IL-10, GCC/GCC, was approximately half that of the frequency in Cuban and Caucasian Americans (0.10 vs 0.19 and 0.23, respectively; p < 0.0001, p = 0.004). Because levels of expression can affect inflammation and immune regulation, differences in cytokine allele frequencies between racial or ethnic groups may contribute to different incidences of autoimmunity and allograft rejection.

Effect of Cytokines and Chemokines (TGF-β, TNF-α, IL-6, IL-10, MCP-1, RANTES) Gene Polymorphisms in Kidney Recipients on Posttransplantation Outcome: Influence of Donor-Recipient Match

Posttransplantation alloantigen-dependent and alloantigen-independent processes are both mediated by cytokines and chemokines. Recently cytokines and chemokines, as well as their receptors, have been shown to be highly polymorphic. The cytokine and chemokine gene polymorphisms are associated with variable production, activity, expression, or ligand-receptor affinity. The aim of our study was to analyze the relation between selected cytokine and chemokine gene polymorphisms in kidney donors and recipients as a function of donor-recipient match and posttransplantation outcome. Polymorphisms transforming growth factor-beta (TGF-beta); tumor necrosis factor-alpha (TNF-alpha); interleukin (IL)-6, and IL-10; monocyte chemoattractant protein-1 (MCP-1); and RANTES (regulated upon activation, normal T-cell expressed and secreted) genes were determined using DNA polymerase chain reaction technology in 268 healthy volunteers, 345 kidney transplant recipients (1997 to 1999), and 298 cadaveric donors. Patients were followed up for 4 to 6 years. The distribution of alleles of selected genes was identical in control subjects, cadaveric donors, and recipients. Low TGF-beta production in both the donor and recipient genotypes was associated with risk for early rejection (6 months) and worse graft function at 4 years. The only tendency for worse graft outcome was observed among donor-recipient combinations mismatched for TGF-beta genotype. Genetic determination of TNF-alpha and IL-10 production was associated with delayed graft function and rejection. IL-6 gene polymorphisms had no effect on the incidence of early acute rejections, but was associated with worse 5-year outcomes. Determinations of MCP-1 overproduction and RANTES-109 TT allele were associated with significant deterioration of graft function. Our data support the hypothesis that the strength of the alloimmune response after transplantation is in part genetically determined. Donor-recipient matching of cytokine gene polymorphisms has a marginal effect.

Donor genomics influence graft events: the effect of donor polymorphisms on acute rejection and chronic allograft nephropathy

BACKGROUND

Organs procured from deceased donors emanate from individuals with diverse genetic backgrounds. Donor organs, therefore, may vary in their response to injury and immune stimuli in a genetically determined manner. We assessed polymorphisms from 244 renal allograft donors to better understand the impact of donor polymorphisms on selected transplant outcomes.

METHODS

Donor genomic DNA restriction fragment length polymorphisms were assayed for evidence of common cytokine [interleukin (IL)-2, IL-6, IL-10, tumor necrosis factor (TNF)-alpha, TGF-beta, interferon (IFN)-gamma] and chemokine (CCR2, CCR5) polymorphisms. Associations between donor polymorphisms and graft events were determined using chi-square, linear regression, and Kaplan-Meier analyses.

RESULTS

Several genotypic polymorphisms demonstrated a modest association with acute rejection, including the transforming growth factor (TGF)-beta T/C codon 10 (P= 0.027) and the CCR5 G/A 59029 (P= 0.039) genes by chi-square analysis. Notably, the presence of the T allele in the IFN-gamma gene (+874) demonstrated a highly significant association with biopsy-proven chronic allograft nephropathy (P < 0.008). This association remained highly significant in a multiple linear regression model that incorporated biopsy-proven acute rejection as a covariate.

CONCLUSION

These data suggest that many of the donor polymorphisms studied in this analysis may influence a recipient's immune response to a renal allograft. However, their greatest impact may be demonstrated in long-term outcomes.

Polymorphism of host response genes: Implications in the pathogenesis and treatment of acute renal failure

Acute inflammatory disorders are the result of an interaction between genetic and environmental factors, and are often characterized by an imbalance between pro- and anti-inflammatory host immune responses. Over the past decade, polymorphisms of host response genes have been explored as genetic risk and prognostic markers in the course and severity of acute inflammatory disorders. Increasing evidence supports an important role for inflammatory mechanisms in the pathogenesis of acute renal failure (ARF) following both ischemic and nephrotoxic injury. The use of genetic epidemiology may become a useful tool to identify patients with an altered susceptibility to developing hospital-acquired ARF, and stratify those who may benefit from preventive therapies that modulate host immune responses in a favorable way. This review summarizes the existing experimental and clinical studies supporting the role of inflammation in ARF and critically appraises studies that have examined polymorphism of immune response genes as potential determinants of susceptibility to and severity of acute inflammatory disorders. Conclusions are drawn on the application of genetic epidemiology to the field of ARF and the rationale for further research on the role of genetic markers in ARF.

Cytokine Gene Polymorphisms and Risks of Acute Rejection and Delayed Graft Function after Kidney Transplantation

BACKGROUND

Pretransplantation identification of patients at an increased risk for adverse events would allow more individualized treatment strategies possibly improving long-term outcome. We studied cytokine gene polymorphisms of kidney allograft recipients and their donors to identify factors predisposing for acute rejection (AR) and delayed graft function (DGF).

METHODS

A total of 291 adult cadaver kidney recipients transplanted at a single transplantation centre between 1999 and 2002 were investigated. Recipients and donors were typed for TNF-alpha(-308G/A), TGF-beta1(codon 10T/C, codon 25C/G), IL-10(-1082G/A, -819C/T, -592C/A), IL-6(-174C/G), and IFN-gamma(+874T/A) polymorphisms using a SSP-PCR kit. An AR episode was defined based on clinical and histological findings (Banff criteria). RESULTS.: The incidence of AR was 17%. In univariate statistical analyses recipients with TNF-alpha -308AA-genotype were found to be at a significantly increased risk for rejection (odds ratio [OR] 5.0, 95% CI 3.0-8.3, P = 0.003). The association was independent from the patient-donor HLA-mismatch status. In addition, patients with IL-10 ACCACC, ATAATA, GCCATA (-1082A/G, -819C/T, -592C/A, respectively) haplotypes were predisposed to rejection (OR 1.9, 95% CI 1.1-3.1, P = 0.016). Further, the combination of recipient TGF-beta1 25GG-genotype and donor IL-10 -819T-allele was associated with rejection (OR 1.8, 95% CI 1.1-3.0, P = 0.027). These variables remained significant risk factors also in a multivariate logistic regression analysis. The incidence of DGF was 22%. The risk was increased by a donor TNF-alpha -308GA-genotype (OR 1.6, 95% CI 1.1-2.6, P = 0.040).

CONCLUSIONS

Our results confirm that cytokine gene polymorphisms influence the outcome of kidney transplantation. Our data especially identify the TNF-alpha -308AA-genotype as a factor predisposing for AR episodes.

Relevance of IL10, TGFbeta1, TNFalpha, and IL4Ralpha gene polymorphisms in kidney transplantation: a collaborative transplant study report

Single nucleotide polymorphisms (SNPs) of cytokine genes have been shown to influence cytokine plasma levels. Cytokines are important mediators during organ graft rejection. It was reported that certain cytokine genotypes are associated with improved kidney graft survival. In the present study, SNPs within the IL10 promoter gene, the first exon of the TGFbeta1 gene, the TNFalpha promoter gene, and the IL4Ralpha gene were analyzed in 2298 first and 1901 repeat cadaver kidney recipients. We found no significant effect on the survival rate of first grafts. Among retransplants, we observed that recipients who were homozygous for the high TNFalpha producer genotype -308 A had a significantly lower graft survival rate than patients who were carriers of the low producer genotype -308 G (at 3 years: 63.0% vs. 79.5%; pcorrected = 0.0116). The results of this large-scale study suggest that IL10, TGFbeta1, TNFalpha, and IL4Ralpha cytokine genotypes do not affect the survival of primary kidney grafts. The outcome of retransplants appears to be affected by TNFalpha genotypes only.

Impaired Kidney Graft Survival is Associated with the TNF-α Genotype

BACKGROUND

The TNF2 allele at position -308 of the tumor necrosis factor (TNF)-alpha gene is associated with high TNF production. The purpose was to study the association of this gene polymorphism with rejection episodes and graft survival after kidney transplantation.

METHODS

A retrospective analysis of transplant outcomes of patients who only had been treated with one single form of immunosuppression consisting of cyclosporine, azathioprine, and prednisolon was performed.

RESULTS

We found that 115 (73%) patients had the TNF1/TNF1 genotype, whereas 42 (27%) were TNF2 positive. There was no difference in the overall acute rejection frequency between these two groups (50% in each), but our data showed a non-significant tendency towards a higher frequency of steroid resistant rejections in the TNF2 positive group (57% vs. 40%). There was no significant difference in graft survival between the two genotype groups, although an early tendency towards worse survival was seen in TNF2 recipients. However, the TNF2 positive recipients with rejection episodes had far worse graft survival compared with the TNF1/TNF1 recipients with rejection episodes (P<0.02). No difference was seen between the two genotype groups in patients without rejection episodes.

CONCLUSION

Our data propose that potentially high TNF producers with the TNF2 allele do not have an increased risk for rejection episodes, but if rejection episodes occur, they have a significantly increased risk for early graft loss. TNF production may intensify rejection, but is not a primary factor for the induction of such acute immune activation.

Renovascular disease is associated with low producer genotypes of the anti-inflammatory cytokine interleukin-10

Cytokines are important mediators of inflammatory and proliferative responses in disease states including atherosclerosis. Genetic variations in cytokine production could potentially influence the outcome of these responses. The aim of this study was to determine whether cytokine gene polymorphism might influence the development of atherosclerotic renal artery stenosis. Sixty-six patients with atherosclerotic renal artery stenosis and 100 normal healthy individuals were genotyped for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-2 promoter region polymorphism. TNF-a, TNF-d, and IL-10 microsatellite polymorphisms were also analyzed. The frequency of the anti-inflammatory cytokine IL-10 promoter (-1082 A positive) GA and AA genotypes which are associated with low production were higher in the patient group when compared to the control group. The AA-TT-AA homozygous genotype combination of three single-nucleotide polymorphisms at -1082, -819, and -592 in the IL-10 gene was also observed at a higher frequency in the patient group compared to the controls. The frequency of TNF-alpha, IL-6, and IL-2 polymorphisms did not show any significant difference between the patient and control groups. To correlate IL-10 genotypes with differences in IL-10 protein expression, in vitro mRNA and protein levels were analyzed in lipopolysaccharide-stimulated peripheral blood mononuclear cells from 22 patients with renal artery stenosis and 33 controls. Individuals genotyped as A positive at position -1082 produced lower levels of IL-10 protein and had lower copy numbers of mRNA when compared to individuals genotyped as A negative in both patient and control groups. The increased frequency of the low producer IL-10 promoter, -1082 A-positive genotype in patients with renal artery stenosis, suggests that IL-10 may protect against the development of atherosclerotic renovascular disease.