Polymorphisms in CTLA-4 predict de novo donor specific antibody formation after kidney transplantation

Polymorphisms in genes involved in regulating follicular helper T cell differentiation predict de novo donor-specific antibody formation after liver transplantation

BACKGROUND

De novo donor-specific antibodies (dnDSAs) significantly affect the long-term outcomes of liver transplantation (LT), highlighting the importance of risk prediction. Follicular helper T (Tfh) cells have been implicated in dnDSA formation after transplantation. Considering the influence of immune response gene polymorphisms on transplantation outcomes, we investigated the association between polymorphisms in Tfh cell-related genes and dnDSA formation after LT.

METHODS

Fifty-three living-donor LT patients were included in this study. Single nucleotide polymorphisms (SNPs) were identified in six Tfh cell-related genes crucial for differentiation and maturation (BCL6, CXCR5, CXCL13, ICOS, CD40L, and IL-21); their association with the development of dnDSA after LT was evaluated.

RESULTS

Among the 53 recipients, 9 developed dnDSAs. BCL6 and IL-21 SNPs showed potential associations with dnDSA formation, enabling risk stratification.

CONCLUSIONS

Variations in Tfh cell-related genes may predispose individuals to dnDSA formation after LT, emphasizing the importance of genetic factors for predicting post-transplant complications.

Impact of CD 28, CD86, CTLA-4 and PD-1 genes polymorphisms on acute renal allograft rejection and graft survival among Egyptian recipients

To study the impact of four gene polymorphisms on acute renal allograft rejection (AR) and graft survival among Egyptian population. These 4 gene polymorphisms include: (1) CD 28 (rs3116496), (2) CD86 (rs1129055), (3) CTLA-4 (rs3087243), (4) PD-1 (rs2227982). This is a non-concurrent cohort study including 50 kidney transplant recipients diagnosed histopathologically as (AR) [study group] and another 50 matched allograft recipients without AR [control group]. Blood samples were taken from both groups and subjected to genotyping for the selected four genetic polymorphisms by TaqMan genotyping assay. The difference in genotypic distribution of CD 28: rs3116496 and CD86: rs1129055 wasn't statistically significant between the study and control groups (P = 0.22 and 0.33 respectively) and also both polymorphisms had no effect on graft survival (P = 0.36 and 0.74 respectively) while the addition of C allele to IVS3 +17T/C polymorphism in CD28 gene showed a protective effect against AR (P = 0.03). CTLA-4: rs3087243 AG genotype showed a protective effect against AR as it was more frequent in no rejection group compared to those with AR (P = 0.001) with a statistically significant impact on graft survival (P < 0.001), while PD-1: rs2227982 AG genotype was equally distributed between both groups (variant of unknown significance). There was no detected association between CD86 polymorphism: rs1129055 and CD 28 polymorphism: rs3116496 with the development of AR. However, C allele of CD 28 IVS3 +17T/C polymorphism and CTLA-4 polymorphism: rs3087243AG genotype both demonstrated a protective effect against AR.

Immune Checkpoints in Solid Organ Transplantation

Allogenic graft acceptance is only achieved by life-long immunosuppression, which comes at the cost of significant toxicity. Clinicians face the challenge of adapting the patients' treatments over long periods to lower the risks associated with these toxicities, permanently leveraging the risk of excessive versus insufficient immunosuppression. A major goal and challenge in the field of solid organ transplantation (SOT) is to attain a state of stable immune tolerance specifically towards the grafted organ. The immune system is equipped with a set of inhibitory co-receptors known as immune checkpoints (ICs), which physiologically regulate numerous effector functions. Insufficient regulation through these ICs can lead to autoimmunity and/or immune-mediated toxicity, while excessive expression of ICs induces stable hypo-responsiveness, especially in T cells, a state sometimes referred to as exhaustion. IC blockade has emerged in the last decade as a powerful therapeutic tool against cancer. The opposite action, i.e., subverting IC for the benefit of establishing a state of specific hypo-responsiveness against auto- or allo-antigens, is still in its infancy. In this review, we will summarize the available literature on the role of ICs in SOT and the relevance of ICs with graft acceptance. We will also discuss the possible influence of current immunosuppressive medications on IC functions.

Evaluation of T-Cell Immune Status of Reduced-Dose Cyclosporine and Everolimus Combination Therapy in Kidney Transplant Patients

BACKGROUND

Kidney transplantation (KT) outcomes have significantly improved with calcineurin inhibitors (CNIs) administration. In recent years, the dose of CNIs has been reduced, and everolimus (EVR) has been used in combination with CNIs to avoid complications from the long-term use of CNIs. However, T-cell immune responses to these protocols have not been fully evaluated. This study evaluated the anti-donor T-cell responses to our CNI-sparing regimen.

METHODS

Fifty-five de novo KT patients were enrolled. Three months after KT, the patients were randomly assigned to either the EVR group, which received low-dose cyclosporine (CsA) (n = 28), or the standard-exposure CsA control group (n = 27), which was treated with both mycophenolate mofetil and methylprednisolone. Graft function, adverse events, and immunologic status were evaluated 3 years after KT. Mixed lymphocyte reaction (MLR) assays were performed to evaluate anti-donor T-cell responses in KT patients.

RESULTS

Both groups maintained graft function well, but total cholesterol levels tended to increase annually in the EVR group. The incidence of cytomegalovirus (CMV) infection tended to be lower in the EVR group, regardless of the CMV serologic status. Immunologic evaluation by MLR assay showed that anti-donor T-cell responses were adequately maintained in both groups.

CONCLUSIONS

EVR starting 3 months after KT can reduce the trough levels of CsA without affecting graft function or compromising the immunosuppressive effects. The EVR combination protocol is expected to reduce CNI toxicity and improve long-term prognosis after KT.

Genetic Polymorphisms in Follicular Helper T Cell-Related Molecules Predispose Patients to De Novo Donor-Specific Antibody Formation After Kidney Transplantation

BACKGROUND

Risk prediction of de novo donor-specific antibody (dnDSA) formation is crucial for understanding the long-term prognostic impact of kidney transplantation (KT). Recently, follicular helper T (Tfh) cells, a subtype of CD4⁺ T cells, have been reported to play an important role in dnDSA formation after solid organ transplantation. Given the growing recognition of the importance of Tfh cells in generating a strong humoral immune response, we examined whether polymorphisms in Tfh cell-related molecules were associated with dnDSA formation after KT.

METHODS

Eighty-three patients who underwent living-donor KT between January 2013 and February 2020 at Hiroshima University Hospital were included in the study. Six Tfh cell-related molecules (BCL6, CXCR5, CXCL13, ICOS, CD40L, and IL21) that are important for Tfh cell differentiation and maturation in secondary lymphoid tissues were investigated. CTLA4, which is important for Tfh-cell activation, was also investigated. Single nucleotide polymorphisms (SNPs) in the genes for these molecules were detected using Taq Man SNP genotyping and evaluated for their association with dnDSA formation after KT.

RESULTS

Of the 83 KT recipients, 8 developed dnDSAs during the observation period. No statistically significant differences were observed in the baseline characteristics between patients with and without dnDSA formation, except for donor age. Among the 7 Tfh cell-related molecules, the incidence of dnDSA formation was associated with CXCR5 and CTLA4 SNPs. Furthermore, combining these 2 SNPs enabled more significant stratification of dnDSA formation.

CONCLUSION

Our findings indicate that genetic polymorphisms in Tfh cell-related molecules are predisposing factors for dnDSA formation after KT.