Recipient and Center Factors Associated With Immunosuppression Practice Beyond the First Year After Liver Transplantation and Impact on Outcomes

Alloreactive T cells temporarily increased in the peripheral blood of patients before liver allograft rejection

T cells are key mediators of alloresponse during liver transplantation (LTx). However, the dynamics of donor-reactive T-cell clones in peripheral blood during a clinical T-cell-mediated rejection (TCMR) episode remain unknown. Here, we collected serial peripheral blood mononuclear cell samples spanning from pre-LTx to 1 year after LTx and available biopsies during the TCMR episodes from 26 rejecting patients, and serial peripheral blood mononuclear cell samples were collected from 96 nonrejectors. Immunophenotypic and repertoire analyses were integrated on T cells from rejectors, and they were longitudinally compared to nonrejected patients. Donor-reactive T-cell clone was identified and tracked by cross-matching with the mappable donor-reactive T-cell receptor repertoire of each donor-recipient pair in 9 rejectors and 5 nonrejectors. Before transplantation, the naive T-cell percentage and T-cell receptor repertoire diversity of rejectors was comparable to that of healthy control, but it was reduced in nonrejectors. After transplantation, the naïve T-cell percentages decreased, and T-cell receptor repertoires were skewed in rejectors; the phenomenon was not observed in nonrejectors. Alloreactive clones increased in proportion in the peripheral blood of rejectors before TCMR for weeks. The increase was accompanied by the naïve T-cell decline and memory T-cell increase and acquired an activated phenotype. Intragraft alloreactive clone tracking in pre-LTx and post-LTx peripheral blood mononuclear cell samples revealed that the pretransplant naïve T cells were significant contributors to the donor-reactive clones, and they temporarily increased in proportion and subsequently reduced in blood at the beginning of TCMR. Together, our findings offer an insight into the dynamic and origin of alloreactive T cells in clinical LTx TCMR cases and may facilitate disease prediction and management.

Immunosuppression regimen and latitude impact keratinocyte carcinoma risk in U.S. liver transplant recipients

Immunosuppression after solid organ transplantation is associated with an increased risk of keratinocyte carcinoma (KC). Despite its established morbidity, KC risk in liver transplant (LT) recipients is understudied, including the contribution of immunosuppression regimen and latitude. A retrospective cohort of 9,966 adult first LT alone recipients alive with their native allograft at 1-year post-LT without prior KC between 2007 and 2016 were identified using linked data from the Organ Procurement and Transplantation Network and Medicare administrative claims. The primary exposures were immunosuppression regimen and latitude of residence. The primary outcome was incident, de novo KC occurring at least 1-year after LT. Adjusted Cox regression analysis stratified by transplant center was used in all analyses. The cohort was 63.4% male, 70.2% White and with median age 61 years (interquartile range, IQR, 54-66) at transplant. Calcineurin inhibitor (CNI) with anti-metabolite combination was independently associated with incident KC when measured as intention-to-treat (adjusted hazard ratio (aHR) 1.21 vs. CNI monotherapy, 95% CI 1.02-1.43, p = 0.026), in a time-updating as-treated analysis (aHR 1.61, 95% CI 1.34-1.93; p < 0.001) and when measured as cumulative exposure (aHR 1.13 per 6-month increase, 95% CI: 1.02-1.33; p = 0.027). More southern latitude of residence was also independently associated with incident KC with an aHR of 1.26 per 5°N decrease towards the Equator (95% CI: 1.08-1.47, p = 0.003). We demonstrate independent effects of CNI with antiM immunosuppression regimen and latitude of residence on the risk of post-LT KC, which will better inform screening practices and immunosuppression management.

Hospitalizations for opportunistic infections following transplantation and associated risk factors: A national cohort study of Medicare beneficiaries

BACKGROUND

Opportunistic infections (OIs) are a significant cause of morbidity and mortality after organ transplantation, though data in the liver transplant (LT) population are limited.

METHODS

We performed a retrospective cohort study of LT recipients between January 1, 2007 and Deceber 31, 2016 using Medicare claims data linked to the Organ Procurement and Transplantation Network database. Multivariable Cox regression models evaluated factors independently associated with hospitalizations for early (≤1 year post transplant) and late (>1 year) OIs, with a particular focus on immunosuppression.

RESULTS

There were 11 320 LT recipients included in the study, of which 13.2% had at least one OI hospitalization during follow-up. Of the 2638 OI hospitalizations, 61.9% were early post-LT. Cytomegalovirus was the most common OI (45.4% overall), although relative frequency decreased after the first year (25.3%). Neither induction or maintenance immunosuppression were associated with early OI hospitalization (all p > .05). The highest risk of early OI was seen with primary sclerosing cholangitis (aHR 1.74; p = .003 overall). Steroid-based and mechanistic target of rapamycin inhibitor-based immunosuppression at 1 year post LT were independently associated with increased late OI (p < .001 overall).

CONCLUSION

This study found OI hospitalizations to be relatively common among LT recipients and frequently occur later than previously reported. Immunosuppression regimen may be an important modifiable risk factor for late OIs.

Cyclosporine vs. tacrolimus after liver transplantation for primary sclerosing cholangitis - a propensity score-matched intention-to-treat analysis

BACKGROUND & AIMS

There is controversy regarding the optimal calcineurin inhibitor type after liver transplant(ation) (LT) for primary sclerosing cholangitis (PSC). We compared tacrolimus with cyclosporine in a propensity score-matched intention-to-treat analysis based on registries representing nearly all LTs in Europe and the US.

METHODS

From the European Liver Transplant Registry (ELTR) and Scientific Registry of Transplant Recipients (SRTR), we included adult patients with PSC undergoing a primary LT between 2000-2020. Patients initially treated with cyclosporine were propensity score-matched 1:3 with those initially treated with tacrolimus. The primary outcomes were patient and graft survival rates.

RESULTS

The propensity score-matched sample comprised 399 cyclosporine-treated and 1,197 tacrolimus-treated patients with PSC. During a median follow-up of 7.4 years (IQR 2.3-12.8, 12,579.2 person-years), there were 480 deaths and 231 re-LTs. The initial tacrolimus treatment was superior to cyclosporine in terms of patient and graft survival, with 10-year patient survival estimates of 72.8% for tacrolimus and 65.2% for cyclosporine (p <0.001) and 10-year graft survival estimates of 62.4% and 53.8% (p <0.001), respectively. These findings were consistent in the subgroups according to age, sex, registry (ELTR vs. SRTR), time period of LT, MELD score, and diabetes status. The acute rejection rates were similar between groups. In the multivariable Cox regression analysis, tacrolimus (hazard ratio 0.72, p <0.001) and mycophenolate use (hazard ratio 0.82, p = 0.03) were associated with a reduced risk of graft loss or death, whereas steroid use was not significant.

CONCLUSIONS

Tacrolimus is associated with better patient and graft survival rates than cyclosporine and should be the standard calcineurin inhibitor used after LT for patients with PSC.

IMPACT AND IMPLICATIONS

The optimal calcineurin inhibitor to use after liver transplantation in patients with primary sclerosing cholangitis has yet to be firmly established. Since randomized trials with long follow-up are unlikely to be performed, multicontinental long-term registry data are essential in informing clinical practices. Our study supports the practice of using tacrolimus instead of cyclosporine in the initial immunosuppressive regimen after liver transplantation for patients with primary sclerosing cholangitis. The retrospective registry-based design is a limitation.

The effectiveness and safety of antibody induction immunosuppression in a large cohort of United States pediatric liver transplant recipients

Data on the potential benefits and risks of induction therapy in pediatric liver transplantation (LT) are limited. This was a retrospective cohort study of 2748 pediatric LT recipients at 26 children's hospitals between January 1, 2006 to May 31, 2017 using data from the pediatric health information system linked to the United Network for Organ Sharing database. The induction regimen was obtained from the pediatric health information system day-by-day pharmacy resource utilization. Cox proportional hazards evaluated the association of induction regimen (none/corticosteroid-only, nondepleting, and depleting) on patient and graft survival. Additional outcomes, including opportunistic infections and posttransplant lymphoproliferative disorder, were studied using multivariable logistic regression. Overall, 64.9% received none/corticosteroid-only induction, whereas 28.1% received nondepleting, 8.3% received depleting, and 2.5% other antibody regimens. Differences in patient characteristics were small, but center practices were heterogeneous. Compared with none/corticosteroid-only induction, nondepleting induction was associated with reduced acute rejection (odd ratio [OR], 0.53; P <.001) but with the increased posttransplant lymphoproliferative disorder (OR, 1.75; P =.021). Depleting induction was associated with improved graft survival (hazard ratio [HR], 0.64; P =.028) but with increased noncytomegalovirus opportunistic infections (OR, 1.46; P =.046). Depleting induction is underused yet may offer long-term benefits in this large multicenter cohort. Greater consensus guidance in this aspect of pediatric LT care is warranted.

Decoding Single-cell Landscape and Intercellular Crosstalk in the Transplanted Liver

BACKGROUND

Liver transplantation (LT) is the most effective treatment for various end-stage liver diseases. However, the cellular complexity and intercellular crosstalk of the transplanted liver have constrained analyses of graft reconstruction after LT.

METHODS

We established an immune-tolerated orthotopic LT mouse model to understand the physiological process of graft recovery and intercellular crosstalk. We employed single-cell RNA sequencing and cytometry by time-of-flight to comprehensively reveal the cellular landscape.

RESULTS

We identified an acute and stable phase during perioperative graft recovery. Using single-cell technology, we made detailed annotations of the cellular landscape of the transplanted liver and determined dynamic modifications of these cells during LT. We found that 96% of graft-derived immune cells were replaced by recipient-derived cells from the preoperative to the stable phase. However, CD206 + MerTK + macrophages and CD49a + CD49b - natural killer cells were composed of both graft and recipient sources even in the stable phase. Intriguingly, the transcriptional profiles of these populations exhibited tissue-resident characteristics, suggesting that recipient-derived macrophages and natural killer cells have the potential to differentiate into 'tissue-resident cells' after LT. Furthermore, we described the transcriptional characteristics of these populations and implicated their role in regulating the metabolic and immune remodeling of the transplanted liver.

CONCLUSIONS

In summary, this study delineated a cell atlas (type-proportion-source-time) of the transplanted liver and shed light on the physiological process of graft reconstruction and graft-recipient crosstalk.