Development and validation of a biomarker index for HCC treatment response.

BACKGROUND: Serum AFP-L3%, AFP, and DCP are useful biomarkers for HCC detection, but their utility in assessing treatment response remains unknown. We aim to evaluate the accuracy of a biomarker model in the detection of posttreatment viable tumors. METHODS: For model derivation, recipients with HCC undergoing liver transplant from 2018 to 2022 who had biomarkers collected within 3 months before transplant were included. We developed a generalized linear model for detecting posttreatment viable tumors with the 3 biomarkers as covariates, which we termed the "LAD Score." An independent cohort of 117 patients with HCC was used for external validation. RESULTS: Among 205 recipients of transplant, 70.2% had evidence of viable tumor on explant. The median LAD score was higher among patients with viable versus nonviable tumors (1.06 vs. 0.465, p < 0.001). The LAD score had a sensitivity of 55.6% and a specificity of 85.1% at the cutoff of 0.927, which was more accurate than imaging for detecting posttreatment viable tumors (AUROC 0.736 vs. 0.643, respectively; p = 0.045). The superior performance of the LAD score over imaging is primarily driven by its greater accuracy in detecting tumors <2 cm in diameter (AUROC of the LAD score 0.721 vs. imaging 0.595, p = 0.02). In the validation data set, the LAD score had an AUROC of 0.832 (95% CI: 0.753, 0.911) with a sensitivity of 72.5% and a specificity of 89.4% at the cutoff of 0.927. CONCLUSIONS: Our findings suggest the utility of LAD score in treatment response assessment after locoregional therapy for HCC, particularly in detecting small tumors. A larger prospective study is in progress to validate its accuracy and evaluate its performance in recurrence monitoring.

Targeting Glycolysis in Alloreactive T Cells to Prevent Acute Graft-Versus-Host Disease While Preserving Graft-Versus-Leukemia Effect.

Alloreactive donor T cells undergo extensive metabolic reprogramming to become activated and induce graft-versus-host disease (GVHD) upon alloantigen encounter. It is generally thought that glycolysis, which promotes T cell growth and clonal expansion, is employed in this process. However, conflicting data have been reported regarding the requirement of glycolysis to induce T cell-mediated GVHD due to the lack of T cell-specific treatments using glycolysis inhibitors. Importantly, previous studies have not evaluated whether graft-versus-leukemia (GVL) activity is preserved in donor T cells deficient for glycolysis. As a critical component affecting the clinical outcome, it is necessary to assess the anti-tumor activity following treatment with metabolic modulators in preclinical models. In the present study, we utilized T cells selectively deficient for glucose transporter 1 (Glut1T-KO), to examine the role of glycolysis exclusively in alloreactive T cells without off-targeting effects from antigen presenting cells and other cell types that are dependent on glycolysis. We demonstrated that transfer of Glut1T-KO T cells significantly improved acute GVHD outcomes through increased apoptotic rates, impaired expansion, and decreased proinflammatory cytokine production. In addition to impaired GVHD development, donor Glut1T-KO T cells mediated sufficient GVL activity to protect recipients from tumor development. A clinically relevant approach using donor T cells treated with a small molecule inhibitor of glycolysis, 2-Deoxy-D-glucose ex vivo, further demonstrated protection from tumor development. These findings indicate that treatment with glycolysis inhibitors prior to transplantation selectively eliminates alloreactive T cells, but spares non-alloreactive T cells including those that protect against tumor growth. The present study has established a definitive role for glycolysis in acute GVHD and demonstrated that acute GVHD can be selectively prevented through targeting glycolysis.

A Clinical Tool to Guide Selection and Utilization of Marginal Donor Livers With Graft Steatosis in Liver Transplantation.

BACKGROUND: Donor liver biopsy (DLBx) in liver transplantation provides information on allograft quality; however, predicting outcomes from these allografts remains difficult. METHODS: Between 2006 and 2015, 16 691 transplants with DLBx were identified from the Standard Transplant Analysis and Research database. Cox proportional hazard regression analyses identified donor and recipient characteristics associated with 30-d, 90-d, 1-y, and 3-y graft survival. A composite model, the Liver Transplant After Biopsy (LTAB) score, was created. The Mini-LTAB was then derived consisting of only donor age, macrosteatosis on DLBx, recipient model for end-stage liver disease score, and cold ischemic time. Risk groups were identified for each score and graft survival was evaluated. P values <0.05 were considered significant. RESULTS: The LTAB model used 14 variables and 5 risk groups and identified low-, mild-, moderate-, high-, and severe-risk groups. Compared with moderate-risk recipients, severe-risk recipients had increased risk of graft loss at 30 d (hazard ratio, 3.270; 95% confidence interval, 2.568-4.120) and at 1 y (2.258; 1.928-2.544). The Mini-LTAB model identified low-, moderate-, and high-risk groups. Graft survival in Mini-LTAB high-risk transplants was significantly lower than moderate- or low-risk transplants at all time points. CONCLUSIONS: The LTAB and Mini-LTAB scores represent guiding principles and provide clinically useful tools for the successful selection and utilization of marginal allografts in liver transplantation.

Challenges, highlights, and opportunities in cellular transplantation: A white paper of the current landscape.

Although cellular transplantation remains a relatively small field compared to solid organ transplantation, the prospects for advancement in basic science and clinical care remain bountiful. In this review, notable historical events and the current landscape of the field of cellular transplantation are reviewed with an emphasis on islets (allo- and xeno-), hepatocytes (including bioartificial liver), adoptive regulatory immunotherapy, and stem cells (SCs, specifically endogenous organ-specific and mesenchymal). Also, the nascent but rapidly evolving field of three-dimensional bioprinting is highlighted, including its major processing steps and latest achievements. To reach its full potential where cellular transplants are a more viable alternative than solid organ transplants, fundamental change in how the field is regulated and advanced is needed. Greater public and private investment in the development of cellular transplantation is required. Furthermore, consistent with the call of multiple national transplant societies for allo-islet transplants, the oversight of cellular transplants should mirror that of solid organ transplants and not be classified under the unsustainable, outdated model that requires licensing as a drug with the Food and Drug Administration. Cellular transplantation has the potential to bring profound benefit through progress in bioengineering and regenerative medicine, limiting immunosuppression-related toxicity, and providing markedly reduced surgical morbidity.

Systemic Complement Activation in Donation After Brain Death Versus Donation After Circulatory Death Organ Donors.

OBJECTIVES: Complement activation in organs from deceased donors is associated with allograft injury and acute rejection. Because use of organs from donors after circulatory death is increasing, we characterized relative levels of complement activation in organs from donors after brain death and after circulatory death and examined associations between donor complement factor levels and outcomes after kidney and liver transplant. MATERIALS AND METHODS: Serum samples from 65 donors (55 donations after brain death, 10 donations after circulatory death) were analyzed for classical, lectin, alternative, and terminal pathway components by Luminex multiplex assays. Complement factor levels were compared between groups, and associations with posttransplant outcomes were explored. RESULTS: Serum levels of the downstream complement activation product C5a were similar in organs from donors after circulatory death versus donors after brain death. In organs from donors after circulatory death, complement activation occurred primarily via the alternative pathway; the classical, lectin, and alternative pathways all contributed in organs from donors after brain death. Donor complement levels were not associated with outcomes after kidney transplant. Lower donor complement levels were associated with need for transfusion, reintervention, hospital readmission, and acute rejection after liver transplant. CONCLUSIONS: Complement activation occurs at similar levels in organs donated from donors after circulatory death versus those after brain death. Lower donor complement levels may contribute to adverse outcomes after liver transplant. Further study is warranted to better understand how donor complement activation contributes to posttransplant outcomes.

Graft-derived extracellular vesicles transported across subcapsular sinus macrophages elicit B cell alloimmunity after transplantation.

Despite the role of donor-specific antibodies (DSAs) in recognizing major histocompatibility complex (MHC) antigens and mediating transplant rejection, how and where recipient B cells in lymphoid tissues encounter donor MHC antigens remains unclear. Contrary to the dogma, we demonstrated here that migration of donor leukocytes out of skin or heart allografts is not necessary for B or T cell allosensitization in mice. We found that mouse skin and cardiac allografts and human skin grafts release cell-free donor MHC antigens via extracellular vesicles (EVs) that are captured by subcapsular sinus (SCS) macrophages in lymph nodes or analog macrophages in the spleen. Donor EVs were transported across the SCS macrophages, and donor MHC molecules on the EVs were recognized by alloreactive B cells. This triggered B cell activation and DSA production, which were both prevented by SCS macrophage depletion. These results reveal an unexpected role for graft-derived EVs and open venues to interfere with EV biogenesis, trafficking, or function to restrain priming or reactivation of alloreactive B cells.

Increase in Alcoholic Hepatitis as an Etiology for Liver Transplantation in the United States: A 2004-2018 Analysis.

BACKGROUND: Changing opinions on the alcohol abstinence requirement have led to increased liver transplantation (LT) for alcoholic hepatitis (AH). We aimed to determine the trend in LT for AH in the United States and overall and graft survival rates. METHODS: Adult liver-alone and liver-kidney registrations added to the Organ Procurement and Transplantation Network waiting list between 2004 and 2018 were divided into 3 periods (2004-2009, 2010-2013, 2014-2018). Kaplan-Meier survival models illustrated patient and graft survival. RESULTS: Between 2004 and 2018, 529 AH patients were registered for and 254 received LT. By periods, 116, 73, and 340 patients were registered for and 49, 17, and 188 patients received LT, respectively, indicating a increase in LT for AH from 2014 to 2018. Yearly registrants from 2014 to 2018 were 32, 47, 51, 70, and 140, and recipients were 16, 24, 24, 38, and 88, respectively, indicating increases of 338% and 450% in registrants and recipients, respectively, since 2014. AH patients had the highest 1- and 3-year posttransplant survival (93.2% and 87.3%, respectively) and graft survival (90.4% and 84.8%, respectively) comparing to other LT recipients. CONCLUSIONS: LT for AH in the United States is at an all-time high with an increased overall patient and graft survival.

Factors Associated With Detection and Survival of T1 Hepatocellular Carcinoma in the United States: National Cancer Database Analysis.

BACKGROUND: It remains unknown to what extent hepatocellular carcinomas (HCCs) are detected very early (T1 stage; ie, unifocal <2 cm) in the United States. The aim of this study was to investigate the trends and factors associated with very early detection of HCC and resultant outcomes. METHODS: Patients with HCC diagnosed from 2004 through 2014 were identified from the National Cancer Database. Logistic regression was used to identify factors associated with T1 HCC detection, and Cox proportional hazard analyses identified factors associated with overall survival among patients with T1 HCC. RESULTS: Of 110,182 eligible patients, the proportion with T1 HCC increased from 2.6% in 2004 to 6.8% in 2014 (P<.01). The strongest correlate of T1 HCC detection was receipt of care at an academic institution (odds ratio, 3.51; 95% CI, 2.31-5.34). Older age, lack of insurance, high Model for End-Stage Liver Disease (MELD) score, high alpha-fetoprotein, increased Charlson-Deyo comorbidity score, and nonsurgical treatment were associated with increased mortality, and care at an academic center (hazard ratio [HR], 0.27; 95% CI, 0.15-0.48) was associated with reduced mortality in patients with T1 HCC. Liver transplantation (HR, 0.27; 95% CI, 0.20-0.37) and surgical resection (HR, 0.67; 95% CI, 0.48-0.93) were independently associated with improved survival compared with ablation. This is the first study to examine the trend of T1 HCC using the National Cancer Database, which covers approximately 70% of all cancer diagnoses in the United States, using robust statistical analyses. Limitations of the study include a retrospective study design using administrative data and some pertinent data that were not available. CONCLUSIONS: Despite increases over time, <10% of HCCs are detected at T1 stage. The strongest correlates of survival among patients with T1 HCC are receiving care at an academic institution and surgical treatment.

Medawar's Paradox and Immune Mechanisms of Fetomaternal Tolerance.

Brazilian-born British biologist Dr. Peter Medawar played an integral role in developing the concepts of immunologic rejection and tolerance, which led to him receiving the Nobel Prize "for the discovery of acquired immunologic tolerance" and eventually made organ transplantation a reality. However, at the time of his early work in tolerance, a paradox to his theories was brought to his attention; how was pregnancy possible? Pregnancy resembles organ transplantation in that the fetus, possessing paternal antigens, is a semi-allogeneic graft that can survive without immunosuppression for 9 months. To answer this question, Medawar proposed three hypotheses of how a mother supports her fetus in utero, now known as "Medawar's Paradox." The mechanisms that govern fetomaternal tolerance are still incompletely understood but may provide critical insight into how to achieve immune tolerance in organ transplantation. Here, we review current understanding of the immune factors responsible for fetomaternal tolerance during pregnancy and discuss the potential implications for advances in transplantation science.

Immunomodulatory Activities of the Heparan Sulfate Mimetic PG545.

Heparanase regulates multiple biological activities that enhance tumor growth and metastatic spread. Heparanase cleaves and degrades heparan sulfate (HS), a key structural component of the extracellular matrix that serves as a barrier to cell invasion and also as a reservoir for cytokines and growth factors critical for tumor growth and metastasis. For this reason, heparanase is an attractive target for the development of novel anti-cancer therapies. Pixatimod (PG545), a heparanase inhibitor, has shown promising results in the treatment of multiple tumor types. PG545 offers a diversity of mechanisms of action in tumor therapy that include angiogenic inhibition, inhibition of growth factor release, inhibition of tumor cell migration, tumor cell apoptosis, activation of ER stress response, dysregulation of autophagy, and NK cell activation. Further investigation into the role that heparanase and its inhibitors play in tumor therapy can lead to the development of effective tumor therapies.

Higher thresholds for the utilization of steatotic allografts in liver transplantation: Analysis from a U.S. national database.

BACKGROUND: Historically, liver allografts with >30% macrosteatosis (MaS) on donor biopsy have been associated with early allograft dysfunction and worse graft survival; however, successful outcomes have been reported in small cohorts. This study proposes an elevated MaS threshold for organ utilization without detriment to graft survival. METHODS: The UNOS Standard Transplant Analysis and Research database was evaluated for transplants between 2006-2015. Graft survival up to 1-year was evaluated by Kaplan-Meier (KM) survival analyses, and by univariate and multivariable logistic regression analyses, including donor and recipient characteristics. Odds ratios (OR) with 95% confidence intervals (CI) for risk of graft loss are reported. RESULTS: Thirty-day risk of graft loss was increased with MaS as low as 10-19% (OR [95% CI] 1.301 [1.055-1.605], p<0.0001) and peaked with MaS 50-59% (2.921 [1.672-5.103]). At 1-year, risk of graft loss remained elevated with MaS 40-49% (1.465 [1.002-2.142]) and MaS 50-59% (1.978 [1.281-3.056], p = 0.0224). Multivariable models were created for Lower and Higher MELD recipients and MaS cutoffs were established. In Lower MELD recipients, organs with ≥50% MaS had increased risk of graft loss at 30 days (2.451 [1.541-3.897], p = 0.0008) and 1-year post-transplant (1.720 [1.224-2.418], p = 0.0125). Higher MELD recipients had increased risk of graft loss at 30 days with allografts showing MaS ≥40% (4.204 [1.440-5.076], p = 0.0016). At 1-year the risk remained increased, but MaS was not significant predictor of graft loss.048 [1.131-3.710], p = 0.0616). In both MELD cohorts, organs with MaS levels below threshold had similar survival to those transplanted without a donor biopsy. CONCLUSIONS: In conjunction with recipient selection, organs with MaS up to 50% may be safely used without detriment to outcomes.

GCNT1-Mediated O-Glycosylation of the Sialomucin CD43 Is a Sensitive Indicator of Notch Signaling in Activated T Cells.

Notch signaling is emerging as a critical regulator of T cell activation and function. However, there is no reliable cell surface indicator of Notch signaling across activated T cell subsets. In this study, we show that Notch signals induce upregulated expression of the Gcnt1 glycosyltransferase gene in T cells mediating graft-versus-host disease after allogeneic bone marrow transplantation in mice. To determine if Gcnt1-mediated O-glycosylation could be used as a Notch signaling reporter, we quantified the core-2 O-glycoform of CD43 in multiple T cell subsets during graft-versus-host disease. Pharmacological blockade of Delta-like Notch ligands abrogated core-2 O-glycosylation in a dose-dependent manner after allogeneic bone marrow transplantation, both in donor-derived CD4+ and CD8+ effector T cells and in Foxp3+ regulatory T cells. CD43 core-2 O-glycosylation depended on cell-intrinsic canonical Notch signals and identified CD4+ and CD8+ T cells with high cytokine-producing ability. Gcnt1-deficient T cells still drove lethal alloreactivity, showing that core-2 O-glycosylation predicted, but did not cause, Notch-dependent T cell pathogenicity. Using core-2 O-glycosylation as a marker of Notch signaling, we identified Ccl19-Cre+ fibroblastic stromal cells as critical sources of Delta-like ligands in graft-versus-host responses irrespective of conditioning intensity. Core-2 O-glycosylation also reported Notch signaling in CD8+ T cell responses to dendritic cell immunization, Listeria infection, and viral infection. Thus, we uncovered a role for Notch in controlling core-2 O-glycosylation and identified a cell surface marker to quantify Notch signals in multiple immunological contexts. Our findings will help refine our understanding of the regulation, cellular source, and timing of Notch signals in T cell immunity.

Effects of Immunosuppressive Medications on Mitochondrial Function.

BACKGROUND: Immunosuppressive medications are widely used for the prevention of allograft rejection in transplantation and graft-versus-host disease after allogeneic hematopoietic stem cell transplantation. Despite their clinical utility, these medications are accompanied by multiple off-target effects, some of which may be mediated by their effects on mitochondria. METHODS: We examined the effect of commonly used immunosuppressive reagents, mycophenolate mofetil (MMF), cyclosporine A (CsA), rapamycin, and tacrolimus on mitochondrial function in human T-cells. T-cells were cultured in the presence of immunosuppressive medications in a range of therapeutic doses. After incubation, mitochondrial membrane potential, reactive oxygen species (ROS) production, and apoptotic cell death were measured by flow cytometry after staining with DiOC6, MitoSOX Red, and Annexin V and 7-AAD, respectively. Increases in cytosolic cytochrome c were demonstrated by Western blot. T-cell basal oxygen consumption rates were measured using a Seahorse bioanalyzer. RESULTS: T-cells demonstrated significant levels of mitochondrial depolarization after treatment with therapeutic levels of MMF but not after treatment with CsA, tacrolimus, or rapamycin. Only MMF induced T-cell ROS production and induced significant levels of apoptotic cell death that were associated with increased levels of cytosolic cytochrome c. MMF decreased T-cell basal oxygen consumption within its therapeutic range, and CsA demonstrated a trend toward this result. CONCLUSIONS: The impairment of mitochondrial function by commonly used immunosuppressive reagents may impair T-cell differentiation and function by decreasing energy production, producing toxic ROS, and inducing apoptotic cell death.

Machine perfusion of donor kidneys may reduce graft rejection.

Recent evidence suggests that hypothermic machine perfusion of donor kidneys reduces delayed graft function (DGF). This study addresses the effect of machine perfusion (MP) on allograft rejection in the United States. We assembled a retrospective cohort of patients undergoing kidney-alone transplants in the UNOS database from June 30, 2004 to May 31, 2017. DGF was defined as dialysis requirement in the first week post-transplant; graft rejection was defined at 6 months and 1 year. Multivariable logistic regression adjusted for recipient and donor factors evaluated the effect of MP on DGF and graft rejection. Records for 79 300 kidney transplants meeting inclusion criteria were abstracted, 42% of which underwent MP. MP kidneys came from older donors, were more likely to have been obtained following donation after cardiac death, and had longer cold ischemic times. Rates of DGF and rejection were similar between MP and static storage kidneys. Following adjustment, recipients of MP kidneys were less likely to experience rejection at 1 year (OR 0.91 [95% CI 0.86-0.97] P = .002), but not at 6 months post-transplantation (OR 0.94 [0.88-1.02] P = .07). This effect persisted following adjustment for cold ischemic time. This study adds to the accumulating evidence demonstrating improved outcomes following MP of kidneys. We encourage protocolized consideration of MP for kidney grafts.

Early Notch Signals Induce a Pathogenic Molecular Signature during Priming of Alloantigen-Specific Conventional CD4+ T Cells in Graft-versus-Host Disease.

Graft-versus-host disease (GVHD) is the most serious complication of allogeneic hematopoietic cell transplantation. Notch signals delivered during the first 48 h after transplantation drive proinflammatory cytokine production in conventional T cells (Tconv) and inhibit the expansion of regulatory T cells (Tregs). Short-term Notch inhibition induces long-term GVHD protection. However, it remains unknown whether Notch blockade blunts GVHD through its effects on Tconv, Tregs, or both and what early Notch-regulated molecular events occur in alloantigen-specific T cells. To address these questions, we engineered T cell grafts to achieve selective Notch blockade in Tconv versus Tregs and evaluated their capacity to trigger GVHD in mice. Notch blockade in Tconv was essential for GVHD protection as GVHD severity was similar in the recipients of wild-type Tconv combined with Notch-deprived versus wild-type Tregs. To identify the impact of Notch signaling on the earliest steps of T cell activation in vivo, we established a new acute GVHD model mediated by clonal alloantigen-specific 4C CD4+ Tconv. Notch-deprived 4C T cells had preserved early steps of activation, IL-2 production, proliferation, and Th cell polarization. In contrast, Notch inhibition dampened IFN-γ and IL-17 production, diminished mTORC1 and ERK1/2 activation, and impaired transcription of a subset of Myc-regulated genes. The distinct Notch-regulated signature had minimal overlap with known Notch targets in T cell leukemia and developing T cells, highlighting the specific impact of Notch signaling in mature T cells. Our findings uncover a unique molecular program associated with the pathogenic effects of Notch in T cells at the earliest stages of GVHD.

Damage-Associated Molecular Patterns Induce Inflammatory Injury During Machine Preservation of the Liver: Potential Targets to Enhance a Promising Technology.

Machine preservation (MP) has emerged as a promising technology in liver transplantation, but the cellular processes occurring during MP have not been characterized. Recent studies have noted the presence of inflammatory molecules generated during MP. We hypothesized that there is a metabolism-dependent accumulation of damage-associated molecular patterns (DAMPs) and inflammatory cytokines during MP and that these molecules provoke inflammation in the graft. To stratify groups by metabolic rate, MP was performed on rat livers from standard donors at 3 different temperatures: room temperature (RT), subnormothermic (30°C), and normothermic (37°C). Static cold storage at 4°C was included as a reference group. Following a 4-hour preservation period, graft reperfusion was performed ex vivo at 37°C (n = 6 for all groups). Levels of DAMPs and inflammatory cytokines were measured, and their biological activity was assessed by determining toll-like receptor (TLR) stimulation, inflammatory gene expression, and activation of cell death pathways. There was a time-dependent increase in levels of DAMPs during MP with high-mobility group box 1 and extracellular DNA levels increasing for all groups (P < 0.05, 30 versus 240 minutes). Tumor necrosis factor α levels in the perfusate also increased during MP for all groups (P < 0.05, 30 minutes versus 240 minutes). Levels of inflammatory molecules correlated with increased activation of TLRs (TLR3, P = 0.02, normothermic machine preservation [MP37] versus machine preservation at room temperature [MPRT]; TLR9, P = 0.02, MP37 versus MPRT). Priming of the NLRP3 inflammasome and activation of cell death pathways were reduced in grafts preserved by MP at room temperature. In conclusion, inflammatory molecules produced during MP have a biological impact on the graft. Therapies to attenuate DAMP-mediated inflammation during MP may further enhance this promising technology.

Circulating mitochondria in organ donors promote allograft rejection.

The innate immune system is a critical regulator of the adaptive immune responses that lead to allograft rejection. It is increasingly recognized that endogenous molecules released from tissue injury and cell death are potent activators of innate immunity. Mitochondria, ancestrally related to bacteria, possess an array of endogenous innate immune-activating molecules. We have recently demonstrated that extracellular mitochondria are abundant in the circulation of deceased organ donors and that their presence correlates with early allograft dysfunction. Here we demonstrate the ability of mitochondria to activate endothelial cells (ECs), the initial barrier between a solid organ allograft and its host. We find that mitochondria exposure leads to the upregulation of EC adhesion molecules and their production of inflammatory cytokines and chemokines. Additionally, mitochondrial exposure causes dendritic cells to upregulate costimulatory molecules. Infusion of isolated mitochondria into heart donors leads to significant increase in allograft rejection in a murine heterotopic heart transplantation model. Finally, co-incubation of human peripheral blood mononuclear cells with mitochondria-treated ECs results in increased numbers of effector (IFN-γ+ , TNF-α+ ) CD8+ T cells. These data indicate that circulating extracellular mitochondria in deceased organ donors may directly activate allograft ECs and promote graft rejection in transplant recipients.

Extracellular Mitochondrial DNA and N-Formyl Peptides in Trauma and Critical Illness: A Systematic Review.

OBJECTIVES: Extracellular mitochondrial DNA and N-formyl peptides released following tissue damage may contribute to systemic inflammation through stimulation of the innate immune system. In this review, we evaluate existing in vivo human data regarding a role for mitochondrial DNA and N-formyl peptides in producing systemic inflammation in trauma and critical illness, investigate the utility of these molecules in risk prediction and clinical decision support, and provide suggestions for standardization of future research. DATA SOURCES: PubMed, Embase (1971-2017). STUDY SELECTION: Studies measuring extracellular mitochondrial DNA and/or N-formyl peptides in acutely ill patients. DATA EXTRACTION: Fifty-four studies were analyzed. Data extracted included article characteristics, methods, results, and performance in clinical prediction. DATA SYNTHESIS: The most common patient types investigated were trauma (19 studies) and sepsis (eight). In studies comparing patient mitochondrial DNA or N-formyl peptide levels to healthy controls, 38 (90.5%) reported significantly elevated mitochondrial DNA levels in patients at first reported time point, as did the one study making this comparison for N-formyl peptides. Nine studies (81.8%) reported significantly elevated plasma/serum mitochondrial DNA levels in at least one time point in patients who developed inflammatory complications of their primary pathology compared with patients without inflammatory complications. For the ability of mitochondrial DNA to predict complications or outcomes, the area under the curve was 0.7 or greater in 84.6% of receiver operating characteristic curves, and 92.9% of odds, adjusted odds, risk, and hazard ratios were statistically significant. CONCLUSIONS: Extracellular mitochondrial DNA levels are elevated early in patients' hospital courses in many acute illnesses and are higher in patients who develop inflammatory complications. Elevated mitochondrial DNA levels may be clinically useful in risk prediction and clinical decision support systems. Further research is needed to determine the role of extracellular N-formyl peptides in systemic inflammation and their possible clinical utility.

Heparan sulfate is a plasma biomarker of acute cellular allograft rejection.

Despite advances in management of immunosuppression, graft rejection remains a significant clinical problem in solid organ transplantation. Non-invasive biomarkers of graft rejection can facilitate earlier diagnosis and treatment of acute rejection. The purpose of this study was to investigate the potential role of heparan sulfate as a novel biomarker for acute cellular rejection. Heparan sulfate is released from the extracellular matrix during T-cell infiltration of graft tissue via the action of the enzyme heparanase. In a murine heart transplant model, serum heparan sulfate is significantly elevated during rejection of cardiac allografts. Moreover, expression of the enzyme heparanase is significantly increased in activated T-cells. In human studies, plasma heparan sulfate is significantly elevated in kidney transplant recipients with biopsy-proven acute cellular rejection compared to healthy controls, recipients with stable graft function, and recipients without acute cellular rejection on biopsy. Taken together, these findings support further investigation of heparan sulfate as a novel biomarker of acute cellular rejection in solid organ transplantation.