Recipient risk factors for acute cellular rejection after orthotopic liver transplant - a single-center, retrospective study

Genome-wide meta-analysis associates donor-recipient non-HLA genetic mismatch with acute cellular rejection post-liver transplantation

BACKGROUND

Acute cellular rejection (ACR) remains a common complication causing significant morbidity post-liver transplantation. Non-human leukocyte antigen (non-HLA) mismatches were associated with an increased risk of ACR in kidney transplantation. Therefore, we hypothesized that donor-recipient non-HLA genetic mismatch is associated with increased ACR incidence post-liver transplantation.

METHODS

We conducted an international multicenter case-control genome-wide association study of donor-recipient liver transplant pairs in 3 independent cohorts, totaling 1846 pairs. To assess genetic mismatch burden, we calculated sum scores for single-nucleotide polymorphism (SNP) mismatch based on all non-HLA functional SNPs, specifically SNPs coding for transmembrane or secreted proteins as they more likely affect the immune system. We analyzed the association between the non-HLA mismatch scores and ACR in a multivariable Cox regression model per cohort, followed by a weighted meta-analysis.

RESULTS

During the first year post-transplantation, 90 of 689 (13%), 161 of 720 (22%), and 48 of 437 (11%) recipients experienced ACR in cohorts 1-3, respectively. Weighted meta-analyses showed that higher mismatch in functional non-HLA SNPs was associated with an increased incidence of ACR (HR 5.99; 95% CI: 1.39-20.08; p=0.011). Moreover, we found a larger effect of mismatch in SNPs coding for transmembrane or secreted proteins on ACR (HR 7.54; 95% CI 1.95-28.79; p=0.003). Sensitivity analyses showed that imputed HLA mismatch did not affect the associations between both non-HLA mismatch scores and ACR.

CONCLUSIONS

Donor-recipient mismatch of functional non-HLA SNPs overall and, especially, of SNPs encoding transmembrane or secreted proteins correlated with 1-year ACR post-liver transplantation. Identifying high-risk immunological burdens between pairs may prevent early graft rejection and aid in personalizing immunosuppressive therapy. Future studies are, however, needed to validate our findings using a genotyped HLA cohort.

Evaluating the Incidence and Risk Factors for Acute Cellular Rejection in a Steroid Sparing Liver Transplant Center

BACKGROUND

Corticosteroids has been the mainstay of immunosuppression (IMS) following liver transplant (LT). With the advent of more potent IMS, complete steroid withdrawal has become possible after LT. However, there is limited data regarding the incidence and risk factors for acute cellular rejection (ACR) in LT recipients on steroid sparing regimens.

OBJECTIVE

To identify the incidence and risk factors of ACR in LT recipients at an urban LT center utilizing a steroid-sparing IMS regimen.

METHODS

This was a single center retrospective study evaluating incidence of ACR in adults (>18 years) who received a LT between 01/01/2008 and 6/30/2019 at a steroid-sparing liver transplant center. Data between patients who had ACR and patients who did not were compared and risk factors were identified by multivariate logistic linear regression.

RESULTS

A total of 266 patients were included in this analysis, of which 18.4% experienced ACR within the first year of LT. Median time to first ACR was 134 (interquartile range [IQR]: 34-246) days. Black race (odds ratio [OR]: 4.39, P < 0.001), continued need for prednisone (OR: 2.80, P = 0.015) and cytomegalovirus (CMV) viremia (OR: 6.27, P < 0.001)) were independent risk factors for ACR. Tacrolimus use was associated with less ACR (OR: 0.33, P = 0.013).

CONCLUSION AND RELEVANCE

Steroid sparing regimens for IMS post-LT were not associated with an increased incidence of ACR when compared to reported ACR rates in literature. Potential risk factors for ACR include Black race, the use of prednisone maintenance IMS therapy, and CMV viremia.

Safety of Tacrolimus Monotherapy within 12 Months after Liver Transplantation in the Era of Reduced Tacrolimus and Mycophenolate Mofetil: National Registry Study

Tacrolimus monotherapy is accepted as a feasible option during early post-liver transplantation as per current international consensus guidelines. However, its effects in the recent era of reduced tacrolimus (TAC) and mycophenolate mofetil (MMF) remain unclear. Liver recipients who either received TAC monotherapy from the treatment onset or switched from TAC/MMF to TAC-mono within 12 months (TAC-mono group; n = 991) were chronologically matched to patients who continued to receive TAC/MMF (TAC/MMF group; n = 991) at the corresponding time points on time-conditional propensity scores. Outcomes within 12 months after matched time points were compared. Biopsy-proven rejection (TAC/MMF: 3.5% vs. TAC-mono: 2.6%; p = 0.381) and graft failure (0.2% vs. 0.7%; p = 0.082) were similar in both groups. However, the decline in eGFR was 3.1 mL/min/1.73 m2 (95% CI: 0.8-5.3) greater at six months (p = 0.008) and 2.4 mL/min/1.73 m2 (95% CI: -0.05-4.9) greater at 12 months (p = 0.048) after the matched time points in TAC-mono group than that in TAC/MMF group. TAC trough levels were also higher in the TAC-mono group throughout the study period. TAC-mono within 12 months after liver transplantation is immunologically safe. However, it can increase the required TAC dose and the decline in renal function than that in TAC/MMF combination therapy.