Early immune biomarkers and intermediate-term outcomes after heart transplantation: Results of Clinical Trials in Organ Transplantation-18

Outcome-Based Risk Assessment of Non-HLA Antibodies in Heart Transplantation: A Systematic Review

BACKGROUND

Current monitoring after heart transplantation (HT) employs repeated invasive endomyocardial biopsies (EMB). Although positive EMB confirms rejection, EMB fails to predict impending, sub-clinical, or EMB-negative rejection events. While non-HLA antibodies have emerged as important risk factors for antibody-mediated rejection (AMR) after HT, their use in clinical risk stratification has been limited. A systematic review of the role of non-HLA antibodies in rejection pathologies has potential to guide efforts to overcome deficiencies of EMB in rejection monitoring.

METHODS

Databases were searched to include studies on non-HLA antibodies in HT recipients. Data collected included: number of patients, type of rejection, non-HLA antigen studied, association of non-HLA antibodies with rejection, and evidence for synergistic interaction between non-HLA antibodies and HLA-DSA responses.

RESULTS

A total of 56 studies met the inclusion criteria. Strength of evidence for each non-HLA antibody was evaluated based on the number of articles and patients in support vs. against their role in mediating rejection. Importantly, despite previous intense focus on the role of anti-MHC class I chain-related gene A (MICA) and anti-angiotensin II type I receptor (AT1R) antibodies in HT rejection, evidence for their involvement was equivocal. Conversely, strength of evidence for other non-HLA antibodies supports that differing rejection pathologies are driven by differing non-HLA antibodies.

CONCLUSION

This systematic review underscores the importance of identifying peri-HT non-HLA antibodies. Current evidence supports the role of non-HLA antibodies in all forms of HT rejection. Further investigations are required to define the mechanisms of action of non-HLA antibodies in HT rejection.

High sensitivity troponin I as a biomarker for cardiac allograft vasculopathy: Evaluation of diagnostic potential and clinical utility

INTRODUCTION

Cardiac allograft vasculopathy (CAV) limits long-term survival in heart transplant (HTx) recipients. The use of biomarkers in CAV surveillance has been studied, but none are used in clinical practice. The predictive value of high-sensitivity troponin I (hsTnI) has not been extensively investigated in HTx recipients.

METHODS

HTx patients undergoing surveillance coronary angiograms and enrolled in the Emory Cardiovascular Biobank had plasma hsTnI measured. CAV grade was assessed using ISHLT nomenclature. Multivariable cumulative link mixed modeling was performed to determine association between hsTnI level and CAV grade. Patients were followed for adverse outcomes over a median 10-year period. Kaplan-Meier survival analysis and Cox proportional hazard modeling were performed.

RESULTS

Three hundred and seventy-two angiograms were analyzed in 156 patients at a median 8.9 years after transplant. hsTnI levels were positively correlated with concurrent CAV grade after adjustment for age, age at transplant, sex, BMI, hypertension, diabetes, hyperlipidemia, estimated glomerular filtration rate, and history of acute cellular rejection (p = .016). In an adjusted Cox proportional hazard model, initial hsTnI level above the median (4.9 pg/mL) remained a predictor of re-transplantation or death (hazard ratio 1.82; 95% confidence interval 1.16-2.90; p = .01).

CONCLUSION

An elevated hsTnI level reflects severity of CAV and is associated with poor long-term outcomes in patients with HTx.

Selection and Interpretation of Molecular Diagnostics in Heart Transplantation

The number of heart transplants performed annually in the United States and worldwide continues to increase, but there has been little change in graft longevity and patient survival over the past 2 decades. The reference standard for diagnosis of acute cellular and antibody-mediated rejection includes histologic and immunofluorescence evaluation of endomyocardial biopsy samples, despite invasiveness and high interrater variability for grading histologic rejection. Circulating biomarkers and molecular diagnostics have shown substantial predictive value in rejection monitoring, and emerging data support their use in diagnosing other posttransplant complications. The use of genomic (cell-free DNA), transcriptomic (mRNA and microRNA profiling), and proteomic (protein expression quantitation) methodologies in diagnosis of these posttransplant outcomes has been evaluated with varying levels of evidence. In parallel, growing knowledge about the genetically mediated immune response leading to rejection (immunogenetics) has enhanced understanding of antibody-mediated rejection, associated graft dysfunction, and death. Antibodies to donor human leukocyte antigens and the technology available to evaluate these antibodies continues to evolve. This review aims to provide an overview of biomarker and immunologic tests used to diagnose posttransplant complications. This includes a discussion of pediatric heart transplantation and the disparate rates of rejection and death experienced by Black patients receiving a heart transplant. This review describes diagnostic modalities that are available and used after transplant and the landscape of future investigations needed to enhance patient outcomes after heart transplantation.

Kaempferide ameliorates cisplatin-induced nephrotoxicity via inhibiting oxidative stress and inducing autophagy

Acute kidney injury (AKI) caused by anti-tumor drugs, such as cisplatin, is a severe complication with no effective treatment currently, leading to the reduction or discontinuation of chemotherapy. Natural products or herbal medicines are gradually considered as promising agents against cisplatin-induced AKI with the advantages of multi-targeting, multi-effects, and less resistance. In this study, we investigated the effects of kaempferide, a natural flavonoid extracted from the rhizome of Kaempferia galanga, in experimental AKI models in vitro and in vivo. We first conducted pharmacokinetic study in mice and found a relative stable state of kaempferide with a small amount of conversion into kaempferol. We showed that both kaempferide (10 μM) and kaempferol (10 μM) significantly inhibited cisplatin-caused injuries in immortalized proximal tubule epithelial cell line HK-2. In AKI mice induced by injection of a single dose of cisplatin (15 mg/kg), oral administration of kaempferide (50 mg/kg) either before or after cisplatin injection markedly improved renal function, and ameliorated renal tissue damage. We demonstrated that kaempferide inhibited oxidative stress and induced autophagy in cisplatin-treated mice and HK-2 cells, thus increasing tubular cell viability and decreasing immune responses to attenuate the disease progression. In addition, treatment with kaempferide significantly ameliorated ischemia-reperfusion-induced renal injury in vitro and in vivo. We conclude that kaempferide is a promising natural product for treating various AKI. This study has great implications for promotion of its use in healthcare products, and help to break through the limited use of cisplatin in the clinic.

New insights on the monitoring of solid-organ allografts based on immune cell signatures

Attaining a fair long-term allograft survival remains a challenge for allogeneic transplantation worldwide. Although the emergence of immunosuppressants has caused noticeable progress in the management of immunologic rejection, proper application of these therapeutics and dose adjustments require delicate and real-time monitoring of recipients. Nevertheless, the majority of conventional allograft monitoring approaches are based on organ damage or functional tests that render them unable to predict the rejection events in early time points before the establishment of a functional alloimmune response. On the other hand, biopsy-based methods include invasive practices and are accompanied by serious complications. In recent years, there have been a myriad of attempts on the discovery of reliable and non-invasive approaches for the monitoring of allografts that regarding a close relationship between allografts and hosts' immune system, most of the attempts have been devoted to the studies on the immune response-associated biomarkers. The discovery of gene and protein expression patterns in immune cells along with their phenotypic characterization and secretome analysis as well as tracking the immune responses in allograft tissues and clinical specimens are among the notable attempts taken to discover the non-invasive predictive markers with a proper coincidence to the pathologic condition. Collectively, these studies suggest a list of candidate biomarkers with ideal potentials for early and non-invasive prediction of allograft rejection and shed light on the way towards developing more standardized and reproducible approaches for monitoring the allograft rejection.

Cardiac allograft vasculopathy: current review and future research directions

Cardiac allograft vasculopathy (CAV) is a pathologic immune-mediated remodelling of the vasculature in transplanted hearts and, by impairing perfusion, is the major cause of late graft loss. Although best understood following cardiac transplantation, similar forms of allograft vasculopathy occur in other vascularized organ grafts and some features of CAV may be shared with other immune-mediated vasculopathies. Here, we describe the incidence and diagnosis, the nature of the vascular remodelling, immune and non-immune contributions to pathogenesis, current therapies, and future areas of research in CAV.

The role of lymphangiogenesis in cardiovascular diseases and heart transplantation

Cardiac lymphangiogenesis plays an important physiological role in the regulation of interstitial fluid homeostasis, inflammatory, and immune responses. Impaired or excessive cardiac lymphatic remodeling and insufficient lymph drainage have been implicated in several cardiovascular diseases including atherosclerosis and myocardial infarction (MI). Although the molecular mechanisms underlying the regulation of functional lymphatics are not fully understood, the interplay between lymphangiogenesis and immune regulation has recently been explored in relation to the initiation and development of these diseases. In this field, experimental therapeutic strategies targeting lymphangiogenesis have shown promise by reducing myocardial inflammation, edema and fibrosis, and improving cardiac function. On the other hand, however, whether lymphangiogenesis is beneficial or detrimental to cardiac transplant survival remains controversial. In the light of recent evidence, cardiac lymphangiogenesis, a thriving and challenging field has been summarized and discussed, which may improve our knowledge in the pathogenesis of cardiovascular diseases and transplant biology.

Abnormal Nailfold Capillaries in Patients after Hand Transplantation

BACKGROUND

The development of graft vasculopathy may play a role in the long-term deterioration of hand grafts. The aim of study was to examine the patterns of the nailfold capillaries in hand transplant recipients.

METHODS

the study was performed on six patients who received hand transplantation. To normalize for the effect of immunosuppression an age- and sex-matched group of 12 patients with active kidney transplant was selected. As an additional control group, 12 healthy volunteers were recruited. Nailfold videocapillaroscopy was performed in all participants. Additionally, serum concentrations of vascular endothelial growth factor (VEGF) were measured.

RESULTS

Videocapillaroscopic examination of the hand allografts revealed significant abnormalities: including capillary disorganization and microhaemorrhages. The number of capillaries was reduced, the vessels were enlarged and branched. Surprisingly, similar, albeit slightly less pronounced, changes were seen in the nailfolds of healthy hands of the limb transplant recipients. In kidney transplant recipients the capillaroscopic pattern was general normal and comparable to healthy individuals. Moreover, serum concentrations of VEGF in all participants correlated with average capillary diameter in capillaroscopy.

CONCLUSIONS

in hand transplant recipients advanced microvascular abnormalities are found in nailfold capillaroscopic pattern in both transplanted and own extremities connected with elevated levels of VEGF.

Mild acute cellular rejection and development of cardiac allograft vasculopathy assessed by intravascular ultrasound and coronary angiography in heart transplant recipients-a SCHEDULE trial substudy

To evaluate the association between mild acute cellular rejection (ACR) and the development of cardiac allograft vasculopathy (CAV) after heart transplantation (HTx). Substudy of the SCHEDULE trial (n = 115), where de novo HTx recipients were randomized to (i) everolimus with early CNI elimination or (ii) CNI-based immunosuppression. Seventy-six patients (66%) were included based on matched intravascular ultrasound (IVUS) examinations at baseline and year 3 post-HTx. Biopsy-proven ACR within year 1 post-HTx was recorded and graded (1R, 2R, 3R). Development of CAV was assessed by IVUS and coronary angiography at year 3 post-HTx. Median age was 53 years (45-61), and 71% were male. ACR was recorded in 67%, and patients were grouped by rejection profile: no ACR (33%), only 1R (42%), and ≥2R (25%). Median ∆MIT (maximal intimal thickness)_BL-3Y was not significantly different between groups (P = 0.84). The incidence of CAV was 49% by IVUS and 26% by coronary angiography with no significant differences between groups. No correlation was found between number of 1R and ∆MIT_BL-3Y (r = -0.025, P = 0.83). The number of 1R was not a significant predictor of ∆MIT_BL-3Y (P = 0.58), and no significant interaction with treatment was found (P = 0.98). The burden of mild ACR was not associated with CAV development.