Combined effects of TGFB1 +869 T/C and +915 G/C polymorphisms on acute rejection risk in solid organ transplant recipients: a systematic review and meta-analysis

Pre-transplant immune profile defined by principal component analysis predicts acute rejection after kidney transplantation

Background

Acute rejection persists as a frequent complication after kidney transplantation. Defining an at-risk immune profile would allow better preventive approaches.

Methods

We performed unsupervised hierarchical clustering analysis on pre-transplant immunological phenotype in 1113 renal transplant recipients from the ORLY-EST cohort.

Results

We identified three immune profiles correlated with clinical phenotypes. A memory immune cluster was defined by memory CD4⁺T cell expansion and decreased naïve CD4⁺T cell. An activated immune cluster was characterized by an increase in CD8⁺T cells and a decreased CD4/CD8 ratio. A naïve immune cluster was mainly defined by increased naïve CD4⁺T cells. Patients from the memory immune profile tend to be older and to have diabetes whereas those from the activated immune profile were younger and more likely to have pre-transplant exposure to CMV. Patients from the activated immune profile were more prone to experience acute rejection than those from other clusters [(HR=1.69, 95%IC[1.05-2.70], p=0.030) and (HR=1.85; 95%IC[1.16-3.00], p=0.011). In the activated immune profile, those without previous exposure to CMV (24%) were at very high risk of acute rejection (27 vs 16%, HR=1.85; 95%IC[1.04-3.33], p=0.039).

Conclusion

Immune profile determination based on principal component analysis defines clinically different sub-groups and discriminate a population at high-risk of acute rejection.

A functional TGFB1 polymorphism in the donor associates with long-term graft survival after kidney transplantation

Background

Improvement of long-term outcomes in kidney transplantation remains one of the most pressing challenges, yet drug development is stagnating. Human genetics offers an opportunity for much-needed target validation in transplantation. Conflicting data exist about the effect of transforming growth factor-beta 1 (TGF-β1) on kidney transplant survival, since TGF-β1 has pro-fibrotic and protective effects. We investigated the impact of a recently discovered functional TGFB1 polymorphism on kidney graft survival.

Methods

We performed an observational cohort study analysing recipient and donor DNA in 1271 kidney transplant pairs from the University Medical Centre Groningen in The Netherlands, and associated a low-producing TGFB1 polymorphism (rs1800472-C > T) with 5-, 10- and 15-year death-censored kidney graft survival.

Results

Donor genotype frequencies of rs1800472 in TGFB1 differed significantly between patients with and without graft loss (P = 0.014). Additionally, the low-producing TGFB1 polymorphism in the donor was associated with an increased risk of graft loss following kidney transplantation (hazard ratio = 2.12 for the T-allele; 95% confidence interval 1.18–3.79; P = 0.012). The incidence of graft loss within 15 years of follow-up was 16.4% in the CC-genotype group and 31.6% in the CT-genotype group. After adjustment for transplant-related covariates, the association between the TGFB1 polymorphism in the donor and graft loss remained significant. In contrast, there was no association between the TGFB1 polymorphism in the recipient and graft loss.

Conclusions

Kidney allografts possessing a low-producing TGFB1 polymorphism have a higher risk of late graft loss. Our study adds to a growing body of evidence that TGF-β1 is beneficial, rather than harmful, for kidney transplant survival.

The rs1800470 Polymorphism of the TGFB1 Gene Is Associated with Myocardial Fibrosis in Heart Transplant Recipients

The transforming growth factor β1 (TGFβ1), whose level may depend on the polymorphism of the TGFB1 gene, is involved in the formation of myocardial fibrosis. Myocardial fibrosis in a cardiac allograft may lead to a heart's structural and functional remodeling and subsequent dysfunction. The frequency of occurrence of alleles and genotypes of the TGFB1 gene polymorphic regions rs1800469, rs1800470, and rs1800471 in heart transplant recipients and their association with graft myocardial fibrosis were analyzed. Carriers of the CC genotype (p = 0.023, OR = 0.12, 95% CI: 0.017-1.0), and more often the G allele of rs1800471 (p = 0.023, OR = 7.76, 95% CI: 1.0-60.20), were found among heart transplant recipients less frequently than among healthy individuals. In patients with ischemic heart disease (IHD), the GG genotype was less common (p = 0.035, OR = 2.68, 95% CI: 1.061-6.793), while the A allele of rs1800469 was found more frequently (p = 0.035, OR = 0.37 95% CI: 0.148-0.942) than in patients with dilated cardiomyopathy (DCM). In heart transplant recipients with the AA genotype of rs1800470, myocardial fibrosis, verified by endomyocardial biopsy, was detected more often than in carriers of the G allele (OR = 10.4, 95% CI: 1.152-94.538, p = 0.013). The revealed differences suggest a relationship between TGFB1 gene polymorphism and graft myocardial fibrosis. Studies on a larger group of patients would make it possible to characterize the influence of genetic factors on the formation of myocardial fibrosis in heart transplant recipients.

Gene polymorphisms and risk of acute renal graft rejection: A field synopsis of meta-analyses and genome-wide association studies

In the present study we systematically re-analyzed results from meta-analyses and genome-wide association studies (GWASs) to assess the credibility of genetic associations with acute rejection risk in renal transplantation. A comprehensive literature search was performed on PubMed, Web of Knowledge, Cochrane library, and Open Grey up to July 2019. Methodological quality of systematic meta-analyses was assessed by the AMSTAR tool. Credibility of genetic associations was assessed by employing the Venice criteria and two Bayesian statistical approaches, the false positive report probability (FPRP) and the Bayesian false discovery probability (BFDP). Sixteen systematic meta-analyses, with a moderate-high quality score (median AMSTAR score: 9, range: 6-11) and 1 GWAS fulfilled the inclusion criteria. Overall, our systematic re-analysis has identified 9 polymorphic variants in 8 genes (ACE, CD28, CTLA-4, CYP3A5, IFNG, TNF-α, PTPRO and CCDC67) as potential risk factors for acute renal graft rejection. At the pre-specified prior probability of 0.001, the 2 SNPs identified by the GWAS (rs7976329 and rs10765602) showed no evidence of noteworthiness under FPRP or BFDP, indicating the possibility of false-positive associations. After applying the Venice criteria in combination with FPRP and BFDP to results from systematic meta-analyses, TT/AT vs AA of IFNG +874 T/A reached moderate epidemiological credibility, while weak evidence of association was found for all the other genetic comparisons. Well-designed GWASs and large replication studies with updated meta-analyses are still needed to identify reliable genetic predictors of acute renal graft rejection.

Relationship between TGF-β1 + 869 T/C and + 915 G/C gene polymorphism and risk of acute rejection in renal transplantation recipients

BACKGROUND

This meta-analysis was conducted to assess the relationship between the transforming growth factor-beta 1 (TGF-β1) + 869 T/C gene polymorphism, + 915 G/C gene polymorphism, and the susceptibility of acute rejection in the recipients with renal transplantation.

METHODS

Relevant studies were searched and identified from the Cochrane Library and PubMed, and eligible investigations were recruited and data were calculated by meta-analysis.

RESULTS

In this study, we found no relationship between either TGF-β1 + 869 T/C or TGF-β1 + 915 G/C gene polymorphism and acute rejection susceptibility in patients with renal transplantation. No association between either gene polymorphism and acute rejection susceptibility in patients with renal transplantation in Caucasian, Asian, or African populations individually was found.

CONCLUSION

The TGF-β1 + 869 T/C and + 915 G/C gene polymorphisms are not associated with acute rejection susceptibility in recipients with renal transplantation.

Blood Groups Distribution and Gene Diversity of the ABO and Rh (D) Loci in the Mexican Population

Objective

To determine the frequency and distribution of ABO and Rh (D) antigens and, additionally, investigate gene diversity and the structure of Mexican populations.

Materials and Methods

Blood groups were tested in 271,164 subjects from 2014 to 2016. The ABO blood group was determined by agglutination using the antibodies anti-A, Anti-B, and Anti-D for the Rh factor, respectively.

Results

The overall distribution of ABO and Rh (D) groups in the population studied was as follows: O: 61.82%; A: 27.44%; B: 8.93%; and AB: 1.81%. For the Rh group, 95.58% of people were Rh (D), and 4.42% were Rh (d). Different distributions of blood groups across regions were found; additionally, genetic analysis revealed that the I^O and I^D allele showed an increasing trend from the north to the center, while the I^A and I^d allele tended to increase from the center to the north. Also, we found more gene diversity in both loci in the north compared with the center, suggesting population structure in Mexico.

Conclusion

This work could help health institutions to identify where they can obtain blood products necessary for medical interventions. Moreover, this piece of information contributes to the knowledge of the genetic structure of the Mexican populations which could have significant implications in different fields of biomedicine.

Pretransplant thymic function predicts acute rejection in antithymocyte globulin-treated renal transplant recipients

Lack of clear identification of patients at high risk of acute rejection hampers the ability to individualize immunosuppressive therapy. Here we studied whether thymic function may predict acute rejection in antithymocyte globulin (ATG)-treated renal transplant recipients in 482 patients prospectively studied during the first year post-transplant of which 86 patients experienced acute rejection. Only CD45RA(+)CD31(+)CD4(+) T cell (recent thymic emigrant [RTE]) frequency (RTE%) was marginally associated with acute rejection in the whole population. This T-cell subset accounts for 26% of CD4(+) T cells. Pretransplant RTE% was significantly associated with acute rejection in ATG-treated patients (hazard ratio, 1.04; 95% confidence interval, 1.01-1.08) for each increased percent in RTE/CD4(+) T cells), but not in anti-CD25 monoclonal (αCD25 mAb)-treated patients. Acute rejection was significantly more frequent in ATG-treated patients with high pretransplant RTE% (31.2% vs. 16.4%) or absolute number of RTE/mm(3) (31.7 vs. 16.1). This difference was not found in αCD25 monclonal antibody-treated patients. Highest values of both RTE% (>31%, hazard ratio, 2.50; 95% confidence interval, 1.09-5.74) and RTE/mm(3) (>200/mm(3), hazard ratio, 3.71; 95% confidence interval, 1.59-8.70) were predictive of acute rejection in ATG-treated patients but not in patients having received αCD25 monoclonal antibody). Results were confirmed in a retrospective cohort using T-cell receptor excision circle levels as a marker of thymic function. Thus, pretransplant thymic function predicts acute rejection in ATG-treated patients.