The Relative Importance of Cytokine Gene Polymorphisms in the Development of Early and Late Acute Rejection and Six-Month Renal Allograft Pathology

Influence of TGFB1 and CTLA4 polymorphisms on calcineurin inhibitors dose and risk of acute rejection in renal transplantation

Organ transplant is often the treatment of choice as it extends and improves patient life. Immunosuppressive treatment, which prevents acute rejection of the organ, is used in transplant patients to prevent the loss of transplant. The aim of the study was to determine the impact of the CTLA4 (+49A>G, rs231775) and the TGF-β1 (-800G>A, rs1800468) polymorphisms on the therapeutic effect of immunosuppressive drugs (cyclosporine-CsA, tacrolimus-TAC) and the risk of acute rejection in renal transplant patients. The analysis of the CTLA4 +49A>G and the TGF-β1 -800G>A polymorphisms was carried out in 392 patients after kidney transplant using real-time PCR. The CTLA4 +49A>G polymorphism did not affect CsA or TAC dose, ratio of drug concentration to dose (C/D), and blood concentrations. As for the TGF-β1 -800G>A polymorphism, patients with the GA genotype required lower TAC doses compared to the GG genotype (TAC 12 h: 3.63 mg vs 5.3 mg, TAC 24 h: 2.38 mg vs 3.29 mg). Comparing the C/D ratio in both groups (TAC 12 h and TAC 24 h), higher C/D ratio was observed in patients with the GA genotype. These results indicate that patients with the A allele require slightly lower doses of TAC. The results suggest that the TGF-β1 -800 G>A polymorphism may influence the TAC dose, while the +49A>G polymorphism of the CTLA4 gene does not correlate with the dose of CsA or TAC. The analysis of the biochemical parameters of the renal profile showed no impact of the CTLA4 and the TGF-β1 polymorphisms on the risk of organ rejection.

Precision Medicine in Kidney Transplantation: Just Hype or a Realistic Hope?

Desirable outcomes including rejection- and infection-free kidney transplantation are not guaranteed despite current strategies for immunosuppression and using prophylactic antimicrobial medications. Graft survival depends on factors beyond human leukocyte antigen matching such as the level of immunosuppression, infections, and management of other comorbidities. Risk stratification of transplant patients based on predisposing genetic modifiers and applying precision pharmacotherapy may help improving the transplant outcomes. Unlike certain fields such as oncology in which consistent attempts are being carried out to move away from the "error and trial approach," transplant medicine is lagging behind in implementing personalized immunosuppressive therapy. The need for maintaining a precarious balance between underimmunosuppression and overimmunosuppression coupled with adverse effects of medications calls for a gene-based guidance for precision pharmacotherapy in transplantation. Technologic advances in molecular genetics have led to increased accessibility of genetic tests at a reduced cost and have set the stage for widespread use of gene-based therapies in clinical care. Evidence-based guidelines available for precision pharmacotherapy have been proposed, including guidelines from Clinical Pharmacogenetics Implementation Consortium, the Pharmacogenomics Knowledge Base National Institute of General Medical Sciences of the National Institutes of Health, and the US Food and Drug Administration. In this review, we discuss the implications of pharmacogenetics and potential role for genetic variants-based risk stratification in kidney transplantation. A single score that provides overall genetic risk, a polygenic risk score, can be achieved by combining of allograft rejection/loss-associated variants carried by an individual and integrated into practice after clinical validation.

Impact of Proinflammatory Cytokine Gene Polymorphisms and Circulating CD3 on Long-Term Renal Allograft Outcome in Egyptian Patients

The extant study aimed to explore the influence of two cytokines TNF-α - 308 and IFN-γ + 874 gene polymorphism on development of renal transplant rejection and to investigate the feasibility of Th1 cytotoxic immune reaction (CD3). It includes 152 kidney recipients were divided into two subgroups: 76 stable graft functions (SGF) and 76 allograft dysfunctions (AD) compared with 56 healthy individuals as control group. TNF-α - 308 G > A and IFN-γ + 874 A > T genetic polymorphisms were characterized using ARMS-PCR technique. CD3 protein expression was measured using ELISA Kit. The effect on transplant outcome was analyzed where, statistically significant differences of TNF-a-308 G/A were observed between AD group when compared to SGF group (OR = 0.296, 95% CI = 0.091-0.965, p = .031) in AG genotype (intermediate producer genotype). Also, AD group displayed a statistically significant increase of IFN-γ + 874 TT (high producer genotype) when compared to SGF group (OR = 0.290, 95% CI = 0.127-0.665, p = .003). The expression of CD3⁺ T lymphocytes in recipients with allograft dysfunction was statistically higher than that with stable allograft function and control groups (732 ± 76, 235 ± 51 and 442 ± 50) respectively and (p ≤ 0.001). In conclusion, IFN-γ + 874 T and TNF-α - 308 A alleles are risk alleles for renal transplant rejection and these two single nucleotide polymorphisms (SNPs) may be implicated in the tendency of rejection after renal transplantation. CD3 may be used as non-invasive biomarker in monitoring of rejection and avoid exposing patients for biopsy risks and sampling error.

Analysis of 75 Candidate SNPs Associated With Acute Rejection in Kidney Transplant Recipients: Validation of rs2910164 in MicroRNA MIR146A

BACKGROUND

Identifying kidney allograft recipients who are predisposed to acute rejection (AR) could allow for optimization of clinical treatment to avoid rejection and prolong graft survival. It has been hypothesized that a part of this predisposition is caused by the inheritance of specific genetic variants. There are many publications reporting a statistically significant association between a genetic variant, usually in the form of a single-nucleotide polymorphism (SNP), and AR. However, there are additional publications reporting a lack of this association when a different cohort of recipients is analyzed for the same single-nucleotide polymorphism.

METHODS

In this report, we attempted to validate 75 common genetic variants, which have been previously reported to be associated with AR, using a large kidney allograft recipient cohort of 2390 European Americans and 482 African Americans.

RESULTS

Of those variants tested, only 1 variant, rs2910164, which alters the expression of the microRNA MIR146A, was found to exhibit a significant association within the African American cohort. Suggestive variants were found in the genes CTLA and TLR4.

CONCLUSIONS

Our results show that most variants previously reported to be associated with AR were not validated in our cohort. This shows the importance of validation when reporting the associations with complex clinical outcomes such as AR. Additional work will need to be done to understand the role of MIR146A in the risk of AR in kidney allograft recipients.

Predictive Value of Interleukin 2 and Interleukin 8 on Early Rejection in Living Related Kidney Transplant Recipients

INTRODUCTION

Early diagnosis of rejection in kidney transplant (KTx) recipients is of paramount importance for long-term graft survival. Cytokines play an important role in rejection via activating T cells. Neutrophil accumulation in the graft indicates cell-mediated rejection. Cellular infiltration is mediated through chemoattractant factors. The aim of this study was to investigate the relationship between graft function and serum levels of interleukin 2 (IL-2) and interleukin 8 (IL-8) in KTx.

METHOD

Sixty-five patients undergoing KTx were enrolled in the study. Serum samples of IL-2 and IL-8 were collected the day before the operation, on postoperative days 1 and 7 day, and during the first and third month after the onset of rejection. The enzyme-linked immunosorbent assay method was used to determine the IL-2 and IL-8 values.

RESULTS

A total of 9 (13.8%) patients had rejection documented on biopsy samples. Fifty-six patients had stable graft function (SGF). IL-2 and IL-8 values before KTx of both the rejected and SGF patients were not statistically different. Univariate analysis revealed that IL-2 and IL-8 were correlated with rejection (P = .046, P = .015). IL-8 levels were higher in the rejection group compared to the SGF group on the seventh day and first month postoperatively (P = .023, P = .038). The rejection group maintained higher levels of IL-8 for 11 days (range: 7-30) compared to the SGF group (P = .002) and the IL-8 levels correlated with serum creatinine levels (r = 0.621, P = .001). IL-2 levels were higher in the rejection group on days 1 and 7 compared to the SGF group (P = .042, P = .031). IL-2 and IL-8 levels were correlated with low eGFR in the third month in the rejection group (r = 0.421, P = .037; r = 0.518, P = .008).

CONCLUSION

Determining the cytokine levels in the early post-KTx period may be helpful in tailoring immunosuppressive regimens in patients with a risk of rejection.

Serum and Urinary Levels of Tumor Necrosis Factor-Alpha in Renal Transplant Patients

OBJECTIVES

Allograft rejection is an important cause of early and long-term graft loss in kidney transplant recipients. Tumor necrosis factor-alpha promotes T-cell activation, the key reaction leading to allograft rejection. Here, we investigated whether serum and urinary tumor necrosis factor-alpha levels can predict allograft rejection.

MATERIALS AND METHODS

This study included 65 living related-donor renal transplant recipients with mean follow-up of 26 ± 9 months. Serum and urinary tumor necrosis factor-alpha levels were measured at pretransplant and at posttransplant time points (days 1 and 7 and months 3 and 6); serum creatinine levels were also monitored during posttransplant follow-up. Standard enzyme-linked immunoabsorbent assay was used to detect tumor necrosis factor-alpha levels. Clinical variables were monitored.

RESULTS

Nine of 65 patients (13.8%) had biopsy-proven rejection during follow-up. Preoperative serum and urinary tumor necrosis factor-alpha levels were not significantly different when we compared patients with and without rejection. Serum tumor necrosis factor-alpha levels (in pg/mL) were significantly higher in the allograft rejection versus nonrejection group at day 7 (11.5 ± 4.7 vs 15.4 ± 5.8; P = .029) and month 1 (11.1 ± 4.8 vs 17.8 ± 10.9; P =.003). Urinary tumor necrosis factor-alpha levels (in pg/mL) were also elevated in the allograft rejection versus the nonrejection group at days 1 (10.2 ± 2.5 vs 14.1 ± 6.8; P = .002) and 7 (9.8 ± 2.2 vs 14.5 ± 2.7; P < .001) and at months 1 (8.0 ± 1.7 vs 11.8 ± 2.4; P < .001), 3 (7.7 ± 1.6 vs 9.6 ± 1.7; P = .002), and 6 (7.4 ± 1.6 vs 8.9 ± 0.9; P = .005).

CONCLUSIONS

Our preliminary findings suggest that tumor necrosis factor-alpha has a role in diagnosing renal transplant rejection. Serum and urinary tumor necrosis factor-alpha levels may be a possible predictor for allograft rejection.

Genetics of acute rejection after kidney transplantation

Treatment of acute rejection (AR) following kidney transplantation has improved in recent years, but there are still limitations to successful outcomes. This review article covers literature in regard to recipient and donor genetics of AR kidney and secondarily of liver allografts. Many candidate gene and some genome-wide association studies (GWASs) have been conducted for AR in kidney transplantation. Genetic associations with AR in kidney and liver are mostly weak, and in most cases, the associations have not been reproducible. A limitation in the study of AR is the lack of sufficiently large populations that account for population stratification to study the AR phenotype which in this era occurs in <10% of transplants. Furthermore, the AR phenotype has been difficult to define and the definitions of classifications have evolved over time. Literature related to the pharmacogenomics of tacrolimus is robust and has been validated in many studies. Associations between gene expression and AR are emerging as markers of outcomes and AR classification. In the future, combinations of pretransplant genotype for AR risk prediction, genotype-based immune suppressant dosing, and pharmacogenomic markers to select AR maintenance or treatment and expression markers from biopsies may provide valuable clinical tools for guiding treatment.

Analysis of OPTN/UNOS registry suggests the number of HLA matches and not mismatches is a stronger independent predictor of kidney transplant survival

HLA matching and mismatching, while inversely related, are not exact opposites. Here we determined the independent effects of HLA matching and mismatching on outcomes in deceased donor kidney transplant recipients. The United Network for Organ Sharing database (1995-2012) was utilized and analyzed for delayed graft function, one-year acute rejection, and death-censored graft survival using combined multivariable models including HLA matching and mismatching. Sensitivity analyses were performed using the subgroup of deceased donor kidney transplant patients after 2003 with more uniform HLA nomenclature and resampling analyses using bootstrapping on complete data available from 96,236 recipients. Individually, both HLA matching and mismatching showed significant associations with graft survival. Adjusting the model to take into account both matching and mismatching simultaneously, the degree of HLA mismatching lost significance while matching continued to have a significant prediction for delayed graft function, the one-year acute rejection rate, and graft survival. Sensitivity analyses and bootstrapping showed similar results for all studied outcomes. Thus, analysis of this large cohort demonstrates the apparent greater association of HLA matching over HLA mismatching on both early allograft events as well as graft survival. Future analyses should preferentially utilize HLA matching as a covariate over mismatching for accurately reflecting impact on graft outcomes.

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.

Clinical and pathological analyses of transplant glomerulopathy cases

AIM

Transplant glomerulopathy (TG) is included as one of the criteria of chronic active antibody-mediated rejection (c-AMR) in Banff 09 classification. In this report, we discuss the clinical and pathological analyses of cases of TG after renal transplantation.

PATIENTS

TG was diagnosed in 86 renal allograft biopsy specimens (BS) obtained from 50 renal transplant patients followed up at our institute between January 2006 and October 2012. We retrospectively reviewed the data of these 86 BS and 50 patients.

RESULTS

Among the 50 patients, 42 (84%) had a history of acute rejection (AR); of these, 30 (60%) had acute antibody-mediated rejection (a-AMR). Among the 86 BS of TG, the TG was mild in 35 cases (cg1 in Banff classification), moderate in 28 cases (cg2) and severe in 23 cases (cg3). Peritubular capillaritis was present in 74 BS (86%), transplant glomerulitis in 65 (76%), interstitial fibrosis and tubular atrophy (IF/TA) in 71 (83%), thickening of the peritubular capillary (PTC) basement membrane in 72 (84%), and interstitial inflammation in 40 (47%). C4d deposition in the PTC was present in 49 BS (57%); 39 of these 49 BS showed diffuse C4d deposits in the PTC (C4d3), while the remaining 10 BS showed focal deposits (C4d2). Diffuse C4d deposition in the glomerular capillaries (GC) was seen in 70 BS (81%), while focal C4d deposition in the GC was seen in 9 (11%). In the assay using plastic beads coated with HLA antigen performed in 67 serum samples obtained in the peri-biopsy period, circulating ant-HLA alloantibody was detected in 55 (82%); in 33 of the 55 (49%) samples, donor-specific antibodies (DSA) were detected. Among our study, the findings in 22 BS (26%) fully met the criteria for c-AMR in Banff '09 classification, including TG, C4d deposition in the PTC and presence of DSA, while those in 27 BS were suspicious of c-AMR. Deterioration of the renal allograft function after the biopsies was seen in 31 patients (62%), of which 11 lost their graft.

CONCLUSIONS

We suggest that histopathological changes of transplant glomerulopathy might be accompanied by inflammation of the microvasculature, such as transplant glomerulitis and peritubular capillaritis, thickening of the peritubular capillary basement membrane, and circulating anti-HLA antibodies. C4d deposition in the PTC is not always present in biopsy specimens of TG. We speculated that C4d deposition in the GC, rather than that in the PTC might be a more characteristic manifestation of TG. Many of the patients with TG had a history of AR. Anti-HLA antibody Class II, particularly when the antibody was DSA Class II, appeared to be associated with the development of TG. The prognosis of grafts exhibiting TG was not too good even under the currently used immunosuppressive protocol.

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

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

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.

A genetic predisposition to produce low levels of IL-10 is related to depressive symptoms: a pilot study of patients with end stage renal disease

OBJECTIVE

Heightened levels of inflammation may be associated with an increased risk of depression, particularly among those with inflammatory medical conditions. Although elevated rates of both systemic inflammation and depression have been documented among patients with end stage renal disease (ESRD), the link between these factors has received little empirical evaluation. The goal of this pilot study was to investigate the association between cytokine gene polymorphisms (that are known to influence pro- and anti-inflammatory cytokine production) and depressive symptoms among patients with ESRD.

METHODS

Ninety-three patients with ESRD completed the Beck Depression Inventory-II and the disease-related symptom subscale of the Kidney Disease Quality of Life short form. Patients were genotyped for eight single nucleotide polymorphisms in genes coding for pro-inflammatory (TNF-α, IL-6, IFN-γ) and anti-inflammatory (IL-10, TGF-β1) cytokines.

RESULTS

Regression analyses indicated that patients with the A/A genotype for the IL-10 -1082 polymorphism (lower IL-10 producers) reported significantly greater depressive symptoms than G allele carriers (higher IL-10 producers; b = 0.22, P = 0.011), even after controlling for relevant covariates.

CONCLUSION

These findings provide some support for cytokine theories of depression in the medically ill, and specifically for the protective role of anti-inflammatory processes. Further research is needed to confirm these preliminary results and to explore the possibility of identifying subtypes of depressed patients based on inflammatory profiles, and those who may benefit from anti-inflammatory therapies.

Antibody-mediated rejection in kidney transplantation: a review

Antibody mediated rejection (AMR) poses a significant and continued challenge for long term graft survival in kidney transplantation. However, in the recent years, there has emerged an increased understanding of the varied manifestations of the antibody mediated processes in kidney transplantation. In this article, we briefly discuss the various histopathological and clinical manifestations of AMRs, along with describing the techniques and methods which have made it easier to define and diagnose these rejections. We also review the emerging issues of C4d negative AMR, its significance in long term allograft survival and provide a brief summary of the current management strategies for managing AMRs in kidney transplantation.

Validation of single nucleotide polymorphisms associated with acute rejection in kidney transplant recipients using a large multi-center cohort

There have been numerous reports proposing a statistically significant association between a genetic variant, usually in the form of a single nucleotide polymorphism (SNP), and acute rejection (AR). Unfortunately, there are additional publications reporting a lack of association with AR when a different cohort of recipients was analyzed for the same SNP. The objective of this report was to attempt replication of these published finding in our own kidney allograft recipient cohort. We analyzed 23 genetic variants, previously reported to have a significant association with AR, using a cohort of 969 clinically well-defined kidney transplant recipients. Only one SNP, rs6025 (Leiden mutation), within the coagulation factor V gene, showed a significant association with a P-value of 0.011 in a race-adjusted analysis and a P-value of 0.0003 in multiple variable analysis. An additional SNP, rs11706052 in IMPDH2, gave a modest P-value of 0.044 using multiple variable analysis, which is not significant when multiple testing is taken into consideration. Our results suggest that careful validation of previously reported associations with AR is necessary, and different strategies other than candidate gene studies can help to identify causative genetic variants associated with AR.

Recommendations for the assessment and reporting of multivariable logistic regression in transplantation literature

Multivariable logistic regression is an important method to evaluate risk factors and prognosis in solid organ transplant literature. We aimed to assess the quality of this method in six major transplantation journals. Eleven analytical criteria and four documentation criteria were analyzed for each selected article that used logistic regression. A total of 106 studies (6%) out of 1,701 original articles used logistic regression analyses from January 1, 2005 to January 1, 2006. The analytical criteria and their respective reporting percentage among the six journals were: Linearity (25%); Beta coefficient (48%); Interaction tests (19%); Main estimates (98%); Ovefitting prevention (84%); Goodness-of-fit (3.8%); Multicolinearity (4.7%); Internal validation (3.8%); External validation (8.5%). The documentation criteria were reported as follows: Selection of independent variables (73%); Coding of variables (9%); Fitting procedures (49%); Statistical program (65%). No significant differences were found among different journals or between general versus subspecialty journals with respect to reporting quality. We found that the report of logistic regression is unsatisfactory in transplantation journals. Because our findings may have major consequences for the care of transplant patients and for the design of transplant clinical trials, we recommend a practical solution for the use and reporting of logistic regression in transplantation journals.

Intragraft expression of the IL-10 gene is up-regulated in renal protocol biopsies with early interstitial fibrosis, tubular atrophy, and subclinical rejection

Grafts with subclinical rejection associated with interstitial fibrosis and tubular atrophy (SCR+IF/TA) show poorer survival than grafts with subclinical rejection without IF/TA (SCR). Aiming to detect differences among SCR+IF/TA and SCR, we immunophenotyped the inflammatory infiltrate (CD45, CD3, CD20, CD68) and used a low-density array to determine levels of T(H)1 (interleukin IL-2, IL-3, gamma-interferon, tumor necrosis factor-alpha, lymphotoxin-alpha, lymphotoxin-beta, granulocyte-macrophage colony-stimulating factor) and T(H)2 (IL-4, IL-5, IL-6, IL-10, and IL-13) transcripts as well as of IL-2R (as marker for T-cell activation) in 31 protocol biopsies of renal allografts. Here we show that grafts with early IF/TA and SCR can be distinguished from grafts with SCR on the basis of the activation of IL-10 gene expression and of an increased infiltration by B-lymphocytes in a cellular context in which the degree of T-cell activation is similar in both groups of biopsies, as demonstrated by equivalent levels of IL-2R mRNA. These results suggest that the up-regulation of the IL-10 gene expression, as well as an increased proportion of B-lymphocytes in the inflammatory infiltrates, might be useful as markers of early chronic lesions in grafts with SCR.

Association of high IFN-gamma plasma levels with low B-cell counts in renal transplant recipients with stable long-term graft function

Recently, we reported that patients with long-term stable good graft function had higher interferon-gamma (IFN-gamma) and lower IL-4 plasma levels late as compared with early post-transplant. These patients had more often detectable CD3(+)CD4(+)CD25(+)IFN-gamma(+)Foxp3(+) peripheral blood lymphocytes (PBL) late post-transplant than patients with impaired graft function. We therefore speculated that high plasma IFN-gamma late post-transplant might contribute to the maintenance of graft acceptance. Using ELISA and four-color flow cytometry, plasma cytokines and PBL subpopulations were measured in 65 renal transplant recipients with stable graft function late post-transplant. High IFN-gamma plasma levels were associated with low CD19(+) B PBL (r = -0.329; p = 0.009) and low activated CD3(+)CD8(+)DR(+) T PBL (r = -0.266; p = 0.035). Plasma IFN-gamma increased with time post-transplant (r = 0.288; p = 0.022) and was not associated with the dose of immunosuppressive drugs (p = n.s.). High plasma IFN-gamma was not associated with serum creatinine (r = 0.038; p = 0.765). Five patients showed evidence of chronic allograft nephropathy in previous biopsies and none of them exhibited increased plasma IFN-gamma. In patients with good long-term graft function, high IFN-gamma plasma levels were associated with low numbers of B PBL and activated CD8(+) T PBL. High IFN-gamma plasma levels might prevent the development of an immunological alloresponse and thereby contribute to the maintenance of graft acceptance.

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.

Effect of cytokine and pharmacogenomic genetic polymorphisms in transplantation

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

Relevance of MICA and other non-HLA antibodies in clinical transplantation

The clinical importance of HLA-specific antibodies for organ allograft outcome is well established. In the past few years, there has been an increasing interest in non-HLA antigens as targets of injury in organ transplant recipients. This increased interest has been spurred by the fact that HLA-identical kidney transplants also undergo immunological rejections. Polymorphisms within non-HLA genes associated with evoking an immune response to alloantigens are currently being studied for their association with transplant outcome. Non-HLA antigens, such as the polymorphic MHC class I-related chain A (MICA), expressed on endothelial cells have been implicated in the pathogenesis of hyperacute, acute and chronic organ allograft rejections. Use of endothelial cells as targets may clarify the specificities of other clinically relevant non-HLA antibodies in graft rejections. This review summarizes past and current knowledge of the clinical importance and specificities of non-HLA antibodies, and mechanisms by which these antibodies may contribute to graft destruction in clinical transplantation. The aims of current research into the role of non-HLA antigens and their genetics in predicting outcome are to develop an improved insight into the basic science of transplantation and to develop a risk or prognostic index for use in the clinical setting. Non-HLA antibody responses are receiving increasing interest in acute and chronic rejection and specificity, affinity, and pathogenicity need to be investigated to estimate their contribution. Undoubtedly, this will continue to be an area of interest in terms of fully understanding the role of non-HLA antigens as targets of immune-mediated injury and the potential for clinical intervention.

Immunosuppressive drug therapy and subclinical acute renal allograft rejection: impact and effect

The incidence of subclinical acute rejection (SCAR) varies between 5% and 15% with current maintenance immunosuppressive drug regimens. Despite many similarities between SCAR and clinical acute rejection exist, the inflammatory activated cell infiltrates are not completely identical while graft cytokine profiles and counteractive immune responses are characterized by subtle differences that could explain why SCAR is not accompanied by immediate graft dysfunction. Evidence that SCAR contributes to chronic allograft damage (interstitial fibrosis and tubular atrophy) and negatively affects graft outcome is counterbalanced by the scarcity of controlled data proving the beneficial effect of SCAR treatment. The development of sensitive and specific noninvasive methods to monitor the immune status of the graft by using mRNA determinations, gene expression analysis (microarrays), proteomic analysis, and magnetic resonance spectroscopy, can help to ultimately replace protocol biopsies and also contribute to the further unraveling of the complex underlying immunological mechanisms responsible for SCAR. The latter would enable clinicians to preemptively make strategic adjustments to immunosuppressive therapy in an attempt to further improve renal allograft survival and clinical care of the transplant patient.

The value of serum neopterin, interferon-gamma levels and interleukin-12B polymorphisms in predicting acute renal allograft rejection

Acute rejection remains a poor predictor of graft outcome. In this study, we measured serum levels of interferon (IFN)-gamma and neopterin by enzyme-linked immunosorbent assay and a single nucleotide polymorphism (SNP) within the 3' untranslated region of the interleukin (IL)-12 B gene (1188 A/C) to determine whether either of these factors could predict acute rejection in renal transplantation. Significantly higher early post-transplant neopterin levels (days 5-7; 35.7 versus 19.9 nmol/l) were observed in recipients who subsequently rejected their grafts. Post-transplant neopterin levels showed a strong positive correlation with 1-month creatinine levels (Spearman's correlation 0.62, P < 0.001), suggesting macrophage activation early after transplantation. Pretransplant neopterin and IFN-gamma levels and the IL-12B gene SNP did not predict acute rejection in this small retrospective study. The ability to predict acute rejection non-invasively early after transplantation could lead to individual tailoring of immunosuppressive regimens and perhaps lead eventually to longer graft survival.

Association of cytokine polymorphisms with subclinical progressive chronic allograft nephropathy in Japanese renal transplant recipients: preliminary study

BACKGROUND

The present study calculated the risk of developing subclinical progressive chronic/sclerosing allograft nephropathy (CAN) under tacrolimus-based immunosuppression according to genetic polymorphisms of cytokines and growth factors, and clinical events including delayed graft function (DGF), acute rejection (AR) and cytomegalovirus (CMV) infection.

METHODS

The subjects were 50 recipients with stable graft function more than one year after renal transplantation. The criteria for subclinical progressive CAN were CAN grade 2 or 3 changes on Banff classification and stable serum creatinine (SCr) levels. Ten genetic polymorphisms were assessed.

RESULTS

Eleven patients (22.0%) developed progressive CAN. The mean ages and SCr levels of recipients with and without progressive CAN were 41.2 and 47.1 years, and 1.46 and 1.22 mg/dL, respectively. There were no significant differences in donor age, number of HLA mismatches, DGF or CMV infection. Although the rate of AR episode seemed to be greater in patients with subclinical progressive CAN, the difference did not reach significance (P = 0.093). The frequencies of the interleukin (IL)-2 T-330G TT genotype (P = 0.046) and IL-4 C-590T C allele (P = 0.092) were higher in patients with progressive CAN. In univariate analysis, the presence of IL-2 T-330G TT (OR 4.57, P = 0.044) was associated with CAN development.

CONCLUSION

The presence of IL-2 T-330G TT genotype may be a risk factor for CAN. Further studies with a large number of subjects and analyses of many cytokine polymorphisms would contribute to the ability to make prognostic determinations or tailor immunomodulatory regimens after renal transplantation.

The TNF (-308A) polymorphism is associated with microchimerism in transfused trauma patients

Microchimerism (MC), defined as the persistence of allogeneic cells at low concentrations, is well documented in transfused trauma patients. We hypothesized that genetic polymorphisms linked to cytokine production could contribute to trauma-induced immune modulation and development of microchimerism after transfusion of trauma patients. We used high-throughput SYBR-green-based genotyping of single nucleotide polymorphisms (SNPs) to characterize 59 transfused trauma patients, with MC (n=30) and without MC (n=29), for 4 functionally significant SNPs: TNF (-308), IL 10 (-1082), IFNG (+874), and TGFB1 (+915). We then compared likelihood for development of MC and the magnitude of immune suppression among subjects with and without these selected immune response SNPs. We identified a significant association between TNF (-308A) SNP and both development of MC and diminished immune responsiveness. Hence predisposing genetic factors may explain, in part, why only a subset of trauma patients develops transfusion-associated microchimerism.

Genetic variability of major inflammatory mediators has no impact on the outcome of kidney transplantation

BACKGROUND

Functionally relevant polymorphisms in genes of the Th1 and Th2-inflammatory pathway influence the susceptibility to acute rejection (AR), chronic allograft nephropathy (CAN), and subclinical rejection (SR) as well as graft survival after renal transplantation. Because these findings have not been validated, we sought confirmatory evidence of these associations in a larger group of renal transplant recipients.

METHODS

A total of 436 kidney transplant recipients were genotyped for 9 single nucleotide polymorphisms (TNF-alpha-308G/A, MCP-1-2518A/G, RANTES-403G/A, -109T/C and -28C/G, CCR2+190G/A, IFN-gamma+874A/T, TGF-beta+869T/C and +915G/C) and for the 32-bp indel polymorphism in CCR5. The effects of these polymorphisms on the incidence of AR, SR, CAN and graft survival were analyzed in single locus and haplotype models.

RESULTS

Single locus analysis revealed that there was no significant difference in the distribution of the genotype frequencies between patients with and without AR, and between patients with CAN or SR, and individuals without CAN. Furthermore, no influence of any of the polymorphisms on the long-term graft survival was observed. Haplotype [TGF-beta +869G; TGF-beta +915C] seemed to be associated with the presence of SR (odds ratio: 3.45, 95% confidence interval: 1.19 - 9.99, P=0.023), but the association was nonsignificant due to the insufficient power.

CONCLUSION

In contrast to previous allelic association studies, neither of the polymorphisms has been associated with the outcome of kidney transplantation in the single locus analysis nor in the haplotype model. Our findings reinforce the need for more rigorous research compliant with the currently accepted standards for polymorphism-disease association studies.

Antibodies against MICA antigens and kidney-transplant rejection

BACKGROUND

Good HLA-A, HLA-B, and HLA-DR matches do not guarantee rejection-free renal transplantation. Some kidney transplants fail despite such matches, suggesting that other antigens might be targets for rejection. Major-histocompatibility-complex (MHC) class I-related chain A (MICA) antigens are polymorphic and can elicit antibody production. We sought to determine whether an immune response to MICA antigens might play a role in the failure of kidney allografts.

METHODS

Pretransplantation serum samples from 1910 recipients of kidney transplants from deceased donors were tested for anti-MICA antibodies with an assay in which single MICA antigens were attached to polystyrene microspheres.

RESULTS

Antibodies against MICA alleles were detected in 217 of the 1910 patients (11.4%). The presence of MICA antibodies was associated with renal-allograft rejection. The mean (+/-SE) 1-year graft-survival rate was 88.3+/-2.2% among recipients with anti-MICA antibodies as compared with 93.0+/-0.6% among recipients without anti-MICA antibodies (P=0.01). Among recipients of first kidney transplants, the survival rate was even lower among MICA antibody-positive patients (87.8+/-2.4%) than among MICA antibody-negative recipients (93.5+/-0.6%, P=0.005). In addition, the association of MICA sensitization with reduced graft survival was more evident in kidney-transplant recipients with good HLA matching: among 326 recipients who received well-matched kidneys (0 or 1 HLA-A plus HLA-B plus HLA-DR mismatch), sensitization against MICA was associated with poorer allograft survival (83.2+/-5.8% among those with anti-MICA antibodies vs. 95.1+/-1.3% among those without such antibodies, P=0.002).

CONCLUSIONS

Presensitization of kidney-transplant recipients against MICA antigens is associated with an increased frequency of graft loss and might contribute to allograft loss among recipients who are well matched for HLA.

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.

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.

Evidence for IFN-? up- and IL-4 downregulation late post-transplant in patients with good kidney graft outcome

We found recently that patients with good graft outcome showed higher IFN-gamma and IL-2, and lower IL-10 plasma levels late post-transplant than early post-transplant. In this retrospective study, we compared cytokine plasma levels in 33 symptom-free outpatients with those of 33 renal transplant recipients with early acute rejection (EAR), 29 with chronic rejection (CR), and 34 healthy controls (HC) to assess whether there is evidence for Th1 activation late post-transplant in patients with good graft outcome. Cytokines were measured pre-transplant, one wk, one month, six months, one yr, and two yr after transplantation. Twelve and 24 months post-transplant, IFN-gamma plasma levels were significantly higher (p = 0.001; p = 0.001, respectively) and IL-4 plasma levels significantly lower (p = 0.028; p = 0.003, respectively) in patients with stable graft function than those in controls. Six, 12, and 24 months post-transplant, patients with stable graft function had similar IFN-gamma and IL-4 plasma levels as patients with successfully treated EAR (p = n.s.), and higher IFN-gamma (p = 0.013; p = 0.001; p = 0.0005, respectively) and lower IL-4 (p = 0.007; p = 0.417; p = 0.0001, respectively) plasma levels than patients with CR. These data suggest that increased plasma IFN-gamma and decreased plasma IL-4 late post-transplant might be involved in the induction of mechanisms that facilitate good long-term graft outcome.

Genetic Association of Interleukin-4, Interleukin-10, and Transforming Growth Factor-β Gene Polymorphism With Allograft Function in Renal Transplant Patients

Despite advances in immunosuppressive therapy in the past decade, allograft rejection remains the primary cause for kidney graft failure. Cytokines are known to be important mediators in renal allograft outcome. The aim of the present study was to ascertain whether interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-beta cytokine gene polymorphisms contributed to kidney graft outcome. We evaluated single nucleotide polymorphism in IL-4 (-1098G/T, -590C/T, -33C/T), IL-10 (-1082A/G, -819C/T, -592A/C), and TGF-beta (codon 10 and 25) in 100 renal transplant recipients and 139 normal healthy control using polymerase chain reactions based on sequence-specific primers. Recipients were clinically characterized as rejection episode (RE) versus stable graft function (SGF). The results showed the frequencies of IL-4 -33 T allele in the RE, SGF, and control group to be 7%, 73%, and 28%, respectively. IL-10 -592 A allele frequency was 39% in RE, 26% in SGF, and 28% in the control group. TGF-beta codon 10 T allele was 39% in RE, 35% in SGF, and 53% in control group. In conclusion, this study suggested that some cytokine gene alleles reflected SGF among kidney transplant recipients.

Risk of adverse post-transplant events after kidney allograft transplantation as predicted by CTLA-4 +49 and TNF-α −308 single nucleotide polymorphisms: A preliminary study

Genetic differences between donor and recipient HLA haplotypes are of major importance for transplant rejection. Other genetic variations occurring in genes encoding cytokines and costimulatory molecules also appear to exert an influence on the manner the host immune system recognizes the allograft. The aims of this work were: 1) to study selected single nucleotide polymorphisms (SNPs) at the loci encoding the T-cell regulatory molecule CTLA-4 (CD152), and the cytokines interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10, and transforming growth factor (TGF)-beta1 in a sample of healthy volunteers and a group of kidney-transplanted patients; and 2) to investigate whether an association exists between any of the SNPs studied and acute or chronic rejection, or non-responsiveness to steroid treatment during episodes of acute rejection (AR) after kidney allograft transplantation. When healthy volunteers were compared with transplanted patients, no significant differences were found in the distribution of genetic frequencies for any of the SNPs analyzed. However, in transplanted patients who received a kidney from a living related donor (KdTxL), a statistically significant association was found between carrying the CTLA-4 +49 A/A genotype and protection from experiencing acute rejection. No such association was found in the group of transplanted patients who received a kidney from a cadaveric non-related donor (KdTxCad). In both, KdTxL and KdTxCad patients, responsiveness to steroid treatment during acute rejection was also in association with the CTLA-4 (+49A/G) SNP. The CTLA-4 +49G allele was found at a very low frequency among steroid-resistant compared with steroid-sensitive patients. Finally, a statistically significant association was found between the presence of the TNF-alpha -308A allele and protection to suffer from chronic rejection. The genetic differences found may serve as risk predictors of adverse post-transplant events.

The significance of subclinical rejection and the value of protocol biopsies

Subclinical rejection (SCR) is diagnosed by protocol histology with a maximal prevalence occurring early after transplantation, falling to low levels by 1 year. Needle-core biopsy is safe, and the histology obtained fairly reflects subclinical immune activity. Several studies have consistently shown that SCR is associated with chronic tubulointerstitial damage, subsequent renal dysfunction and reduced graft survival. SCR is effectively treated by pulse corticosteroid therapy, although increased baseline immunosuppression may be necessary. A single randomized clinical trial of biopsy and corticosteroid therapy demonstrated significantly improved early structural and functional outcomes, and a (nonsignificant) 17% risk reduction in 4-year graft survival. Three possible approaches include: no protocol biopsies (usually accompanied by powerful immunosuppression); biopsies only in high-risk recipients (who may be difficult to reliably predict) or universal screening protocol biopsy (comprehensive but limited by cost and resource utilization). The appropriate screening methodology for a transplant unit is both a clinical and an economic decision; influenced by the SCR prevalence and potential gains of treatment, against costs and resource utilization. Further trials to quantify the cost-benefit balance in a typical, heterogeneous recipient population using modern immunosuppression are required.

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.