Acute Cardiac Allograft Rejection Research Articles

Cost-Effectiveness of Cardiovascular Magnetic Resonance for Rejection Surveillance After Cardiac Transplantation in the Australian Health Care System

Heart transplantation is an effective treatment for end-stage congestive heart failure, however, achieving the right balance of immunosuppression to maintain graft function while minimising adverse effects is challenging. Serial endomyocardial biopsies (EMBs) are currently the standard for rejection surveillance, despite being invasive. Replacing EMB-based surveillance with cardiac magnetic resonance (CMR)-based surveillance for acute cardiac allograft rejection has shown feasibility. This study aimed to assess the cost-effectiveness of CMR-based surveillance in the first year after heart transplantation. A prospective clinical trial was conducted with 40 orthotopic heart transplant (OHT) recipients. Participants were randomly allocated into two surveillance groups: EMB-based, and CMR-based. The trial included economic evaluations, comparing the frequency and cost of surveillance modalities in relation to quality-adjusted life years (QALYs) within the first year post-transplantation. Sensitivity analysis encompassed modelled data from observed EMB and CMR arms, integrating two hypothetical models of expedited CMR-based surveillance. In the CMR cohort, 238 CMR scans and 15 EMBs were conducted, versus (vs) 235 EMBs in the EMB group. CMR surveillance yielded comparable rejection rates (CMR 74 vs EMB 94 events, p=0.10) and did not increase hospitalisation risk (CMR 32 vs EMB 46 events, p=0.031). It significantly reduced the necessity for invasive EMBs by 94%, lowered costs by an average of AUD$32,878.61, and enhanced cumulative QALY by 0.588 compared with EMB. Sensitivity analysis showed that increased surveillance with expedited CMR Models 1 and 2 were more cost-effective than EMB (all p<0.01), with CMR Model 1 achieving the greatest cost savings (AUD$34,091.12±AUD$23,271.86 less) and utility increase (+0.62±1.49 QALYs, p=0.011), signifying an optimal cost-utility ratio. Model 2 showed comparable utility to the base CMR model (p=0.900) while offering the benefit of heightened surveillance frequency during periods of elevated rejection risk. CMR-based rejection surveillance in orthotopic heart transplant recipients provides a cost-effective alternative to EMB-based surveillance. Furthermore, it reduces the need for invasive procedures, without increased risk of rejection or hospitalisation for patients, and can be incorporated economically for expedited surveillance. These findings have important implications for improving patient care and optimising resource allocation in post-transplant management.

Oxymatrine combined with rapamycin to attenuate acute cardiac allograft rejection

Background and aimSolid organ transplantation remains a life-saving therapeutic option for patients with end-stage organ dysfunction. Acute cellular rejection (ACR), dominated by dendritic cells (DCs) and CD4+ T cells, is a major cause of post-transplant mortality. Inhibiting DC maturation and directing the differentiation of CD4+ T cells toward immunosuppression are keys to inhibiting ACR. We propose that oxymatrine (OMT), a quinolizidine alkaloid, either alone or in combination with rapamycin (RAPA), attenuates ACR by inhibiting the mTOR–HIF–1α pathway. MethodsGraft damage was assessed using haematoxylin and eosin staining. Intragraft CD11c+ and CD4+ cell infiltrations were detected using immunohistochemical staining. The proportions of mature DCs, T helper (Th) 1, Th17, and Treg cells in the spleen; donor-specific antibody (DSA) secretion in the serum; mTOR–HIF–1α expression in the grafts; and CD4+ cells and bone marrow-derived DCs (BMDCs) were evaluated using flow cytometry. ResultsOMT, either alone or in combination with RAPA, significantly alleviated pathological damage; decreased CD4+ and CD11c+ cell infiltration in cardiac allografts; reduced the proportion of mature DCs, Th1 and Th17 cells; increased the proportion of Tregs in recipient spleens; downregulated DSA production; and inhibited mTOR and HIF-1α expression in the grafts. OMT suppresses mTOR and HIF-1α expression in BMDCs and CD4+ T cells in vitro. ConclusionsOur study suggests that OMT-based therapy can significantly attenuate acute cardiac allograft rejection by inhibiting DC maturation and CD4+ T cell responses. This process may be related to the inhibition of the mTOR–HIF–1α signaling pathway by OMT.

Doppler echocardiography for surveillance of acute cardiac allograft rejection: a 28-year single-center experience.

Endomyocardial biopsies (EMB) are recommended for the detection of acute cardiac rejection (ACR) despite limited sensitivity. We report the long-term post-transplant results of Doppler echocardiography as a noninvasive alternative of routine EMB. Two cohorts of heart transplantation (HT) recipients were chronologically defined as follows: the Dual Monitoring Cohort (DMC) from January 1990 to December 1997 included patients who underwent routine EMB and Doppler echocardiography within 24 hours for ACR surveillance; and the "Echo-First Cohort" (EFC), including patients transplanted from January 1998 to December 2018 with Doppler echocardiography as first-line approach for ACR surveillance. Echocardiographic measurements of interest were collected: early diastolic (E) wave peak velocity; pressure half time (PHT) and isovolumetric relaxation time (IVRT). Post-transplant outcomes were reviewed and the Kaplan-Meier approach was used for survival estimates. Inter-operator variability for ultrasound measurements was investigated. Data were collected from medical records from January 2019 to December 2020. A total of 228 patients were included, 99 patients in the DMC and 129 in the EFC. Overall, 5-, 10- and 15-year survival rates were 65.4%, 55.5% and 44.1% respectively, without any significant difference between the two cohorts (log rank test, P=0.71). Echocardiography variables and EMB findings were associated with a mean area under the receiver operating characteristic curve (AUC-ROC) of 0.73 [95% confidence interval (CI): 0.54-0.91], 0.74 (95% CI: 0.54-0.94) and 0.75 (95% CI: 0.57-0.94) respectively for E wave, PHT and IVRT. IVRT and PHT were significantly decreased, and E wave significantly increased, in case of histologically proven ACR. Inter-operator variability was not significant for E wave and IVRT measurements (P=0.13 and 0.30 respectively). Doppler echocardiography as a first-line method for surveillance of ACR did not impair long-term results after HT. These findings suggest that this non-invasive approach might be a reasonable alternative to systematic EMB, limiting risk and improving the quality of life.

Kiosk 7R-FB-09 - Feasibility of a Non-contrast Rapid Cardiac Magnetic Resonance Protocol in Heart Transplant Recipients for Detection of Acute Cardiac Allograft Rejection: Initial Experience FBom a Developing Country

Kiosk 7R-FB-09 - Feasibility of a Non-contrast Rapid Cardiac Magnetic Resonance Protocol in Heart Transplant Recipients for Detection of Acute Cardiac Allograft Rejection: Initial Experience FBom a Developing Country

Microneedle-mediated transdermal delivery of FK506 for treatment of acute cardiac allograft rejection

FK506 has been widely used to prevent acute rejection in heart transplantation (HT). However, its strong hydrophobicity, poor bioavailability, high pharmacokinetic variability, and narrow therapeutic window are obstacles to its application in HT. It has been demonstrated that localized and sustained immunosuppressant delivery may be a suitable route for FK506 administration. Hence, the objective of this study was to evaluate the efficacy of a FK506-loaded microneedle (FK506 MN) in the treatment of acute rejection in HT. The physicochemical properties of FK506 MN were evaluated, and it exhibited constant release over the course of at least 9 days with a 94.6 % cumulative release rate. Also, the FK506 MN treatment could successfully alleviate acute rejection and prolong allograft survival compared with the untreated group (mean survival time, 12.33 versus 7.25 days). Furthermore, T cell and macrophage infiltration as well as secretion of IL-2, IL-6 and IFN-γ were dramatically reduced in the FK506 MN group. As expected, no hepatoxicity and nephrotoxicity were observed after the application of FK506 MN. Taken together, FK506 MN based drug delivery system provides a novelty strategy to deliver FK506 in heart transplantation, which may be also suitable for other organ transplantations in the future.

Total Lymphoid Irradiation in the Treatment of Heart Transplant Rejection: Single Institution Long-Term Results

Acute cardiac allograft rejection is a major cause of morbidity and mortality post-transplant. Total lymphoid irradiation (TLI) has been shown to cause long-lasting alterations in lymphocyte sub-sets, and thereby induces a state of partial response that is useful to prevent organ transplant rejection. In our previous report, treatment with TLI resulted in decreased episodes of acute rejection and steroid dosage requirements for up to 9.1 years post cardiac transplantation. In this study, we report an update on the short- and long-term effects of TLI in the treatment of cardiac transplant rejection. We performed a retrospective analysis of patients with intractable cardiac allograft transplantation evaluated in the department of radiation oncology at our institution over 23 years (1998-2021). Cardiac allograft rejection was defined as multiple or persistent episodes of rejection despite aggressive immunosuppressive therapy. The prescribed dose was 8 Gy in 10 fractions to be delivered over 5 weeks. All episodes of pathologic acute cardiac rejection, duration of immunosuppression, and episodes of acute infection requiring treatment before and after TLI were documented. Overall survival (OS) was analyzed using Kaplan-Meier method. The median time to first cardiac allograft rejection and the median time to first acute rejection was monitored. Of the 29 patients included, 21 (72.4%) had ISHLT grade 1R, 5 (17.2%), grade 2R, and 2(6.9%) grade 3R rejection. Rejection grade was unknown for 1 patient. The mean number of acute rejections after transplant was 14.4 episodes per patient (range 1-44) with median time to first rejection of 0.63 months. The median radiation dose was 8 Gy (range 7.2-8 Gy) delivered over a mean of 31 days. Treatment was stopped early in 2 (6.5%) patients (after 7.2 Gy and 7.9 Gy) for severe bone marrow suppression and drop in CD4 counts, respectively. The number of rejections dropped from 14.2 to 3.97 per patient over a median time of 29.0 months vs 28.1 months pre and post TLI (p = 0.01). The frequency of ISHLT acute grade 3R rejections decreased from 0.58 to 0.06 episodes per patient pre and post TLI (p = 0.02). Immunosuppressant requirements decreased from 2.83 before TLI to 2.69 after TLI (p = 0.71). Infection rates per patient were 0.71 pre TLI and remained at 0.63 post TLI. Treatment was well tolerated with 4 (13.8%) grade 2 or higher radiation toxicity. Median follow up was 76.3 months. Median and 3-year OS were 53.4 months and 60.9%, respectively. TLI is a safe and effective treatment for control of intractable cardiac rejection. The episodes of acute rejection and immunosuppressant requirements are decreased, but with long-term follow up, these patients continue to experience rejection. However, TLI lowers the frequency of ISHLT moderate to severe rejection episodes for up to 6.4 years. There was no increased risk of severe infections and there were only minimal short- and long-term grade 2 or higher radiation toxicities.

Electrospun polymer fibers modified with FK506 for the long-term treatment of acute cardiac allograft rejection in a heart transplantation model.

FK506, a first-line immunosuppressant, is routinely administered orally and intravenously following heart transplantation. However, frequent administration can result in a substantial psychological burden to patients, resulting in non-adherence to medication. The purpose of our study is to overcome the disadvantages of systemic drug administration by developing a polymer-based delivery system that is tunable and biodegradable and that can release highly hydrophobic FK506 over extended periods to treat or prevent acute cardiac allograft rejection. Using an electrospinning method, long-acting microfibers were prepared, and FK506 appeared to be continuously released for up to 14 days based on the in vitro release profiles. After implanting the microfiber subcutaneously into the abdominals of transplanted rats, it was found that the infiltration of T cells and macrophages and the secretion of interleukin-2 (IL-2) and IL-1β were significantly reduced compared with those of the free FK506 groups. More importantly, the mean survival time (MST) of the PCL-FK506 group was significantly extended in comparison with that of untreated control recipients and free FK506 (MST of untreated control recipients, free FK506, and PCL-FK506 was 8, 26.1, and 37, respectively). In conclusion, we propose that this drug delivery approach would be suitable for developing long-lasting immunomodulatory agents that prolong cardiac graft survival safely and effectively.

IL-37 overexpression promotes endometrial regenerative cell-mediated inhibition of cardiac allograft rejection

BackgroundEndometrial regenerative cells (ERCs) play an important role in attenuation of acute allograft rejection, while their effects are limited. IL-37, a newly discovered immunoregulatory cytokine of the IL-1 family, can regulate both innate and adaptive immunity. Whether IL-37 overexpression can enhance the therapeutic effects of ERCs in inhibition of acute cardiac allograft rejection remains unknown and will be explored in this study.MethodsC57BL/6 mice recipients receiving BALB/c mouse heterotopic heart allografts were randomly divided into the phosphate-buffered saline (untreated), ERC treated, negative lentiviral control ERC (NC-ERC) treated, and IL-37 overexpressing ERC (IL-37-ERC) treated groups. Graft pathological changes were assessed by H&E staining. The intra-graft cell infiltration and splenic immune cell populations were analyzed by immunohistochemistry and flow cytometry, respectively. The stimulatory property of recipient DCs was tested by an MLR assay. Furthermore, serum cytokine profiles of recipients were measured by ELISA assay.ResultsMice treated with IL-37-ERCs achieved significantly prolonged allograft survival compared with the ERC-treated group. Compared with all the other control groups, IL-37-ERC-treated group showed mitigated inflammatory response, a significant increase in tolerogenic dendritic cells (Tol-DCs), regulatory T cells (Tregs) in the grafts and spleens, while a reduction of Th1 and Th17 cell population. Additionally, there was a significant upregulation of immunoregulatory IL-10, while a reduction of IFN-γ, IL-17A, IL-12 was detected in the sera of IL-37-ERC-treated recipients.ConclusionIL-37 overexpression can promote the therapeutic effects of ERCs to inhibit acute allograft rejection and further prolong graft survival. This study suggests that gene-modified ERCs overexpressing IL-37 may pave the way for novel therapeutic options in the field of transplantation.

Cardiovascular Magnetic Resonance for Rejection Surveillance After Cardiac Transplantation.

Endomyocardial biopsy (EMB) is the gold standard method for surveillance of acute cardiac allograft rejection (ACAR) despite its invasive nature. Cardiovascular magnetic resonance (CMR)-based myocardial tissue characterization allows detection of myocarditis. The feasibility of CMR-based surveillance for ACAR-induced myocarditis in the first year after heart transplantation is currently undescribed. CMR-based multiparametric mapping was initially assessed in a prospective cross-sectional fashion to establish agreement between CMR- and EMB-based ACAR and to determine CMR cutoff values between rejection grades. A prospective randomized noninferiority pilot study was then undertaken in adult orthotopic heart transplant recipients who were randomized at 4 weeks after orthotopic heart transplantation to either CMR- or EMB-based rejection surveillance. Clinical end points were assessed at 52 weeks. Four hundred one CMR studies and 354 EMB procedures were performed in 106 participants. Forty heart transplant recipients were randomized. CMR-based multiparametric assessment was highly reproducible and reliable at detecting ACAR (area under the curve, 0.92; sensitivity, 93%; specificity, 92%; negative predictive value, 99%) with greater specificity and negative predictive value than either T1 or T2 parametric CMR mapping alone. High-grade rejection occurred in similar numbers of patients in each randomized group (CMR, n=7; EMB, n=8; P=0.74). Despite similarities in immunosuppression requirements, kidney function, and mortality between groups, the rates of hospitalization (9 of 20 [45%] versus 18 of 20 [90%]; odds ratio, 0.091; P=0.006) and infection (7 of 20 [35%] versus 14 of 20 [70%]; odds ratio, 0.192; P=0,019) were lower in the CMR group. On 15 occasions (6%), patients who were randomized to the CMR arm underwent EMB for clarification or logistic reasons, representing a 94% reduction in the requirement for EMB-based surveillance. A noninvasive CMR-based surveillance strategy for ACAR in the first year after orthotopic heart transplantation is feasible compared with EMB-based surveillance. HREC/13/SVH/66 and HREC/17/SVH/80. ACTRN12618000672257.

Cytosporone B (Csn-B), an NR4A1 agonist, attenuates acute cardiac allograft rejection by inducing differential apoptosis of CD4+T cells

CD4+T cell-mediated acute rejection remains a major factor that affects the early survival of transplanted organs post-transplantation. Here, we reveal that nuclear receptor subfamily 4 Group A member 1 (Nr4A1) was upregulated during cardiac allograft rejection and that the increased Nr4A1 was primarily localized in intragraft-infiltrating CD4+T cells. Nr4A1 acts as a transcription factor with an important role in CD4+T cell apoptosis, differentiation and T cell dysfunction, which indicates that Nr4A1 may play a critical role in transplant rejection. Cytosporone B (Csn-B) is a naturally occurring agonist of Nr4A1, and the role of Csn-B in the physiological process of cardiac rejection is poorly defined. This study constructed an acute rejection model of abdominal heterotopic cardiac transplantation in mice and investigated whether Csn-B could attenuate acute transplant rejection by modulating the CD4+T lymphocyte response. The results showed that Csn-B prolonged murine cardiac allograft survival and reduced inflammation in allografts. Subsequently, it was confirmed that Csn-B functions by inducing non-Treg apoptosis and promoting Treg cell differentiation. Finally, we also confirmed that Csn-B attenuates acute rejection by directly targeting Nr4A1 in CD4+T cells. Our data suggest that Csn-B is a promising novel therapeutic approach for acute cardiac allograft rejection.

Single-Cell RNA sequencing reveals immune cell dynamics and local intercellular communication in acute murine cardiac allograft rejection.

Rationale: Transplant rejection is a major impediment to long-term allograft survival, in which the actions of immune cells are of fundamental importance. However, the immune cell dynamics and local intercellular communication of acute cardiac allograft rejection are not completely clear.Methods: Here we performed single-cell RNA sequencing on CD45+ immune cells isolated from cardiac grafts and spleens in a model of murine heterotopic heart transplantation. Moreover, we applied unsupervised clustering, functional enrichment analysis, cell trajectory construction and intercellular communication analysis to explore the immune cell dynamics and local intercellular communication of acute cardiac allograft rejection at single-cell level. The effect of CXCR3 antagonist and neutralizing antibody against its ligand on allograft rejection and T cell function was evaluated in murine heart transplantation model.Results: We presented the immune cell landscape of acute murine cardiac allograft rejection at single-cell resolution, and uncovered the functional characteristics and differentiation trajectory of several alloreactive cell subpopulations, including Mki67hi CTLs, Ccl5hi CTLs, activated Tregs and alloreactive B cells. We demonstrated local intercellular communication and revealed the upregulation of CXCR3 and its ligands in cardiac allografts. Finally, CXCR3 blockade significantly suppressed acute cardiac allograft rejection and inhibited the alloreactive T cell function.Conclusions: These results provide a new insight into the immune cell dynamics and local intercellular communication of acute cardiac allograft rejection, and suggest CXCR3 pathway may serve as a potential therapeutic target for transplant rejection.

Cardiac magnetic resonance for heart transplant patients

The acute cardiac allograft rejection (ACAR) is the leading cause of mortality in patients with heart transplant. Currently, the endomyocardial biopsy (EMB) is considered to be the gold standard in screening for ACAR, which is an invasive pro­ce­dure with life-threatening complications; however, it does not provide information about the whole myocardium and may give a false negative result in up to 20% of the cases. At the moment, cardiac magnetic resonance imaging (CMR) has be­come a commonly used diagnostic method. It is known to be a noninvasive and reproducible method for determining car­diac ventricular volumes and muscle mass. It provides tis­sue-specific information (myocardial edema, necrosis/fi­bro­sis) using different sequences and contrast agents. The purpose of this study is to evaluate the most promising tech­niques for characterizing myocardial tissue and detecting ACAR using CMR imaging.

Aspirin Attenuates Cardiac Allograft Rejection by Inhibiting the Maturation of Dendritic Cells via the NF-κB Signaling Pathway.

Background: Dendritic cells (DCs) serve as an important part of the immune system and play a dual role in immune response. Mature DCs can initiate immune response, while immature or semi-mature DCs induce immune hyporesponsiveness or tolerance. Previous studies have shown that aspirin can effectively inhibit the maturation of DCs. However, the protective effect of aspirin on acute cardiac allograft rejection has not been studied. The aim of this study was to elucidate the effect of aspirin exert on allograft rejection.Methods: The model of MHC-mismatched (BALB/c to B6 mice) heterotopic heart transplantation was established and administered intraperitoneal injection with aspirin. The severity of allograft rejection, transcriptional levels of cytokines, and characteristics of immune cells were assessed. Bone marrow-derived dendritic cells (BMDCs) were generated with or without aspirin. The function of DCs was determined via mixed lymphocyte reaction (MLR). The signaling pathway of DCs was detected by Western blotting.Results: Aspirin significantly prolonged the survival of cardiac allograft in mouse, inhibited the production of pro-inflammatory cytokines and the differentiation of effector T cells (Th1 and Th17), as well as promoted the regulatory T cells (Treg). The maturation of DCs in the spleen was obviously suppressed with aspirin treatment. In vitro, aspirin decreased the activation of NF-κB signaling of DCs, as well as impeded MHCII and co-stimulatory molecules (CD80, CD86, and CD40) expression on DCs. Moreover, both the pro-inflammatory cytokines and function of DCs were suppressed by aspirin.Conclusion: Aspirin inhibits the maturation of DCs through the NF-κB signaling pathway and attenuates acute cardiac allograft rejection.

Second Line Systemic Treatments Including Extracorporeal Photopheresis Among Patients with Chronic Graft Versus Host Disease (cGVHD) in the United States, 2009-2016

Introduction: Extracorporeal photopheresis (ECP) is a cell-based immunomodulatory therapeutic procedure approved by the FDA for cutaneous T-cell lymphoma (CTCL) among individuals who have not been responsive to other forms of treatment in the United States (US). As clinical evidence accumulated over the years, Centers for Medicare & Medicaid Services (CMS) issued several Medicare National Coverage Decisions (NCDs) for coverage of ECP in patients with acute cardiac allograft rejection or chronic graft versus host disease (cGVHD), who are, refractory to standard immunosuppressive drug treatment. In contrast, per British Committee for Standards in Haematology (BCSH) guidelines on treatment of cGVHD, ECP is recommended as the first option over other 2nd-line systemic treatments including rapamycin (mTOR) inhibitors, pentostatin, rituximab, and imatinib. The objective of this analysis was to describe real-world use of ECP in patients with cGVHD in the US between 2009 and 2016.Methods: A retrospective analysis was conducted using the Truven Health MarketScan® Commercial and Medicare Supplemental claims databases (2009-2016). Adult (≥18 years) cGVHD patients receiving 2nd-line systemic treatments, with continuous health plan enrolment 3 months prior to first cGVHD diagnosis (i.e., baseline period) and 6 months following the initiation of 2nd-line systemic treatment were included. Patient demographic and clinical characteristics were summarized by type of 2nd-line systemic treatment (ECP vs. non-ECP). In addition, treatment patterns including the time from cGVHD diagnosis to initiation of 2nd-line systemic treatment, duration of ECP treatment (ie, time from initiation to end of ECP treatment), and ECP use (proportion of patients receiving ECP treatment among those receiving 1 of the 5 2nd-line systemic treatments) by year were reported. Annual per person all-cause cost for cGVHD patients for emergency room (ER) visits, office visits, and inpatient visits incurred after receiving 2nd-line systemic treatment (ie, the follow-up period) were also reported.Results: Of the 3086 adult cGVHD patients, 663 (21.5% of patients with cGVHD) patients had ≥2 claims for 2nd-line systemic treatments, of which 464 met the continuous enrollment criterion and were included in the study (mean age=49.7 years; 60.1% males). The most commonly reported underlying conditions at baseline were bone marrow transplant (268 [57.8%]), stem cell transplant (280 [60.4%]) and CTCL (25 [5.4%]). The average time from first cGVHD diagnosis to initiation of 2nd-line systemic treatment was 5.4 months. Among patients receiving 2nd-line systemic treatments, 210 (45.3%) received ECP treatment for an average duration of 11.1 months. ECP and non-ECP patients were similar in terms of demographic and clinical characteristics, with organ transplant as the most common underlying condition during the baseline period. As the number of cGVHD patients increased from 16 in 2009 to 100 in 2016, ECP use increased from 31.3% in 2009 to 54.0% in 2016. The total annual all-cause per patient cost was $190,148, including $4619 for ER visits, $8,673 for office visits, and $176,856 for hospitalizations during the follow-up period.Conclusions: Results from the latest US commercial administrative claims data pointed to an increase rate of cGVHD between 2009 and 2016. Of the 464 study patients with cGVHD, 2nd-line systemic treatment was initiated 5.4 months following the first diagnosis of cGVHD. As the number of cGVHD patients increased the rate of ECP use increased over time as well. During the study period, ECP was used by 45.3% of study patients with average duration of 11.1 months. In addition, high economic burden was reported among cGVHD patients receiving 2nd-line systemic treatments. DisclosuresJoshi:Pharmerit International: Employment; Mallinckrodt Pharmaceuticals: Research Funding. Luo:Mallinckrodt Pharmacueticals: Research Funding; Pharmerit International: Employment. Huang:Mallinckrodt Pharmaceuticals: Employment. Mitri:Mallinckrodt: Employment. Lovelace:Mallinckrodt Pharmaceuticals: Employment. Pham:University of California, School of Pharmacy: Employment; Mallinckrodt Pharmaceuticals: Employment. Gao:Mallinckrodt Pharmaceuticals: Consultancy, Employment.

IRF4 ablation in B cells abrogates allogeneic B cell responses and prevents chronic transplant rejection

B cells contribute to chronic transplant rejection by producing donor-specific antibodies and promoting T cell response, but how these processes are regulated at the transcriptional level remains unclear. Herein, we investigate the role of transcription factor interferon regulatory factor 4 (IRF4) in controlling B cell response during chronic transplant rejection. We generated the Irf4gfp reporter mice to determine IRF4 expression in B cell lineage. We then used mice with B cell-specific IRF4 deletion to define the role of IRF4 in B cell response after NP-KLH immunization or allogeneic heart transplantation. In particular, graft survival and histology, as well as B and T cell responses, were evaluated after transplantation. IRF4 is dynamically expressed at different stages of B cell development and is absent in germinal center (GC) B cells. However, IRF4 ablation in the B cell lineage primarily eliminates GC B cells in both naïve and NP-KLH immunized mice. In the transplantation setting, IRF4 functions intrinsically in B cells and governs allogeneic B cell responses at multiple levels, including GC B cell generation, plasma cell differentiation, donor-specific antibody production, and support of T cell response. B cell-specific IRF4 deletion combined with transient CTLA4-Ig treatment abrogates acute and chronic cardiac allograft rejection in naïve recipient mice but not in donor skin-sensitized recipients. B cells require IRF4 to mediate chronic transplant rejection. IRF4 ablation in B cells abrogates allogeneic B cell responses and may also inhibit the ability of B cells to prime allogenic T cells. Targeting IRF4 in B cells represents a potential therapeutic strategy for eliminating chronic transplant rejection.

Circulating growth differentiation factor-15 as a novel biomarker in heart transplant.

AimsThis study aimed to examine (i) whether circulating growth differentiation factor‐15 (GDF‐15) is associated with acute cellular cardiac allograft rejection (ACR); (ii) a longitudinal trend of GDF‐15 after heart transplantation; and (iii) the prognostic value of GDF‐15 in predicting a composite outcome of severe primary graft dysfunction (PGD) and 30 day mortality post‐transplant.Methods and resultsSerum samples were collected before heart transplantation and at every endomyocardial biopsy (EMB) post‐heart transplantation in de novo transplant patients. A total of 60 post‐transplant serum samples were matched to the corresponding EMBs. Seven (12%) were considered International Society for Heart Lung Transplantation Grade 1R ACR, and one (2%) was identified as Grade 2R ACR. GDF‐15 levels in patients with ACR were not different from those in the non‐rejection group (6230 vs. 6125 pg/mL, P = 0.27). GDF‐15 concentration gradually decreased from 8757 pg/mL pre‐transplant to 5203 pg/mL at 4 weeks post‐transplant. The composite adverse outcome of PGD and 30 day mortality was significantly associated with increased post‐operative GDF‐15 (odds ratio: 40; 95% confidence interval: 2.01–794.27; P = 0.005) and high inotrope score post‐transplant (odds ratio: 18; 95% confidence interval: 1.22–250.35; P = 0.01).ConclusionsCirculating GDF‐15 concentration was markedly elevated in patients with end‐stage heart failure and decreased after heart transplantation. GDF‐15 was significantly associated with post‐transplant PGD and mortality. A lack of association between ACR and GDF‐15 did not support routine use of GDF‐15 as a biomarker to detect ACR. However, GDF‐15 may be potentially useful to determine heart transplant recipients at high risk for adverse post‐transplant outcomes. We suggest that GDF‐15 levels in recipient serum can provide risk stratification for severe PGD including death during post‐operative period. This novel biomarker may serve to inform and guide timely interventions against severe PGD and adverse outcomes during the first 4 weeks after transplantation. Further studies to support the utility of GDF‐15 in heart transplantation are required.

IN-HOSPITAL OUTCOMES OF ADMISSIONS AND 30-DAY RE-ADMISSIONS FOR ACUTE ALLOGRAFT REJECTION AFTER HEART TRANSPLANTATION

Purpose The incidence of acute cardiac allograft rejection and mortality after heart transplantation (HT) have declined. We aimed to investigate the clinical outcomes of acute cardiac allograft rejection after HT requiring hospitalization. Methods Two distinct cohort were analyzed. The National Inpatient Sample (NIS) was queried to identify HT recipients admitted for acute rejection between 2015 to 2017 and analyze clinical outcomes and respective predictors. The National Readmission Database (NRD) was utilized to identify patients who underwent heart transplantation from 2016 to 2017 to analyze 30-day readmission. Results A total of 3,790 patients were admitted for HT rejection in the NIS cohort. Serious adverse events such as death in 4.1%, ventricular tachycardia in 5.4%, cardiogenic shock in 10.8% and use of extracorporeal membrane oxygenation in 2.5% were found. Female gender was associated with in-hospital death (odds ratio [OR] 4.48, 95% confidence interval [CI] 1.52-13.1, p=0.006). Younger age and end-stage renal disease were identified as independent predictors of transplant graft failure (OR 0.95, 95% CI 0.93-0.98, p=0.001, OR 3.65, 95% CI 1.22-10.99, p=0.021, respectively). Among 5,817 patients who were admitted for HT in the NRD cohort, 209 (3.6%) were readmitted within 30 days for transplant rejection with most occurring within 15 days. Younger age and female gender were associated with significantly increased risk of 30-day readmission for transplant rejection (OR 0.99, 95% CI 0.98-1.00, p=0.043; OR 1.43, 95% CI 1.00-2.03, p=0.048, respectively). No cases of mortality and utilization of mechanical circulatory support were identified. Conclusion Although early re-admissions for acute rejection after HT are infrequent and not associated with serious adverse effects, overall admissions for acute rejection are not uncommon and serious adverse events occur in a portion of these patients.

Kinetics of generic tacrolimus in heart transplantation: A cautionary note

Tacrolimus is a core component of immunosuppressive regimens. This study compared active pharmaceutical ingredient (API) and dissolution kinetics of branded tacrolimus and formulations from three generic manufacturers (Mylan, Dr. Reddy's, Intas) including samples from patients who suffered acute cardiac allograft rejection. Generic samples showed similar API content compared to branded samples with no major impurities. Capsules that underwent uniformity testing had consistent capsule-to-capsule API. Dissolution testing showed similar profiles between branded tacrolimus and Mylan, but notable differences with Dr. Reddy's and Intas. The approximate maximal inhibitory concentration (IC50) was highest in branded tacrolimus (29 minutes), followed by Mylan (26 minutes), Dr. Reddy's (19 minutes), and Intas (14 minutes) (Student-Newman-Keuls Multiple Comparisons Test; overall ANOVA: p = 0.0199, F = 6.469). This study suggests that the bioavailability of certain generic tacrolimus formulations peak significantly earlier than branded tacrolimus. Further study is needed to determine whether these differences are clinically relevant.

In-Hospital Outcomes of Admissions and 30-day Re-Admissions for Acute Allograft Rejection after Heart Transplantation

Purpose The incidence of acute cardiac allograft rejection and mortality after heart transplantation (HT) have declined. We aimed to investigate the clinical outcomes of acute cardiac allograft rejection after HT requiring hospitalization. Methods Two distinct cohort were analyzed. The National Inpatient Sample (NIS) was queried to identify HT recipients admitted for acute rejection between 2015 to 2017 and analyze clinical outcomes and respective predictors. The National Readmission Database (NRD) was utilized to identify patients who underwent heart transplantation from 2016 to 2017 to analyze 30-day readmission. Results A total of 3,790 patients were admitted for HT rejection in the NIS cohort. Serious adverse events such as death in 4.1%, ventricular tachycardia in 5.4%, cardiogenic shock in 10.8% and use of extracorporeal membrane oxygenation in 2.5% were found. Female gender was associated with in-hospital death (odds ratio [OR] 4.48, 95% confidence interval [CI] 1.52-13.1, p=0.006). Younger age and end-stage renal disease were identified as independent predictors of transplant graft failure (OR 0.95, 95% CI 0.93-0.98, p=0.001, OR 3.65, 95% CI 1.22-10.99, p=0.021, respectively). Among 5,817 patients who were admitted for HT in the NRD cohort, 209 (3.6%) were readmitted within 30 days for transplant rejection with most occurring within 15 days. Younger age and female gender were associated with significantly increased risk of 30-day readmission for transplant rejection (OR 0.99, 95% CI 0.98-1.00, p=0.043; OR 1.43, 95% CI 1.00-2.03, p=0.048, respectively). No cases of mortality and utilization of mechanical circulatory support were identified. Conclusion Although early re-admissions for acute rejection after HT are infrequent and not associated with serious adverse effects, overall admissions for acute rejection are not uncommon and serious adverse events occur in a portion of these patients.

PJ34, a PARP1 inhibitor, attenuates acute allograft rejection after murine heart transplantation via regulating the CD4+ T lymphocyte response.

Acute allografts rejection is the most important factor causing allograft disability for many patients undergoing organ transplantation. PJ34, which is a specific inhibitor of poly(ADP-ribose) polymerase 1, is involved in immune regulation, may be effective in preventing acute cardiac rejection. We performed the models of abdominal heterotopic heart transplantation. PJ34 was injected intraperitoneally daily (20mg/kg/day) starting the day after surgery. The severity of rejection was determined by histology. The mRNA expression levels of cytokines and transcription factors in the grafts were measured by quantitative polymerase chain reaction (qPCR). The proportion and number of T-cell subpopulations in the spleens were analyzed by flow cytometry. In vitro, the effect of PJ34 on allogeneic responses was investigated. We found treatment with PJ34 prolonged allograft survival compared with normal saline treatment. Compared with the control group, PJ34 treatment reduced the proportion of CD4+ IFN-γ+ and CD4+ IL-17A+ cells and increased the percent of CD4+ IL-4+ and CD4+ Foxp3+ cells in the spleens. In vitro, PJ34 treatment significantly inhibited the mRNA levels of IFN-γ and IL-17A and promoted the mRNA levels of TGF-β and FOXP-3 in activated CD4+ T cells. Modulating the CD4+ T lymphocyte response with PJ34 could attenuate acute allografts rejection after murine heart transplantation. These findings indicate that PARP1 may be a promising therapeutic target to attenuate acute cardiac allograft rejection.