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ObjectiveTo identify potential race, sex and age disparities in performance of transthoracic echocardiography (TTE) over several decades.MethodsTTE reports from five academic and community sites within a single integrated healthcare system were linked to 100% Medicare fee-for-service claims from 1 January 2005 to 31 December 2017. Multivariable Poisson regression was used to estimate adjusted rates of TTE utilisation after the index TTE according to baseline age, sex, race and comorbidities among individuals with ≥2 TTEs. Non-white race was defined as black, Asian, North American Native, Hispanic or other categories using Medicare-assigned race categories.ResultsA total of 15 870 individuals (50.1% female, mean 72.2±12.7 years) underwent a total of 63 535 TTEs (range 2–55/person) over a median (IQR) follow-up time of 4.9 (2.4–8.5) years. After the index TTE, the median TTE use was 0.72 TTEs/person/year (IQR 0.43–1.33; range 0.12–26.76). TTE use was lower in older individuals (relative risk (RR) for 10-year increase in age, 0.91, 95% CI 0.89 to 0.92, p<0.001), women (RR 0.97, 95% CI 0.95 to 0.99, p<0.001) and non-white individuals (RR 0.95, 95% CI 0.93 to 0.97, p<0.001). Black women in particular had the lowest relative use of TTE (RR 0.92, 95% CI 0.88 to 0.95, p<0.001). The only clinical conditions associated with increased TTE use after multivariable adjustment were heart failure (RR 1.04, 95% CI 1.00 to 1.08, p=0.04) and chronic obstructive pulmonary disease (RR 1.05, 95% CI 1.00 to 1.10, p=0.04).ConclusionsAmong Medicare beneficiaries with multiple TTEs in a single large healthcare system, the median TTE use after the index TTE was 0.72 TTEs/person/year, although this varied widely. Adjusted for comorbidities, female sex, non-white race and advancing age were associated with decreased TTE utilisation.

Kidney transplant recipients are usually treated with cyclosporine. This drug is used to suppress the patient's immune defense system, which normally responds to the donor organ graft by attempting its rejection. Although this drug is effective, it has significant side effects and the best treatment regimen is difficult to determine. A review was undertaken of the effectiveness and long-term effects of cyclosporine used for 461 kidney transplants. There were 82 kidneys given by living relatives of the recipient and 379 grafts taken from unrelated cadaver donors. Over this 10-year period four different treatment regimens were used with progressively decreasing doses of cyclosporine; a fifth group received a second or subsequent kidney transplant and these patients received triple therapy of cyclosporine, azathioprine and prednisone. Mortality, usually due to sepsis (body-wide infection), was less than 5 percent. Most of the lost kidneys occurred within two months of transplant. In 49 percent of the cadaver kidneys and 17 percent of the living relative kidneys, the transplanted kidney never functioned at all. During long-term follow-up there was a higher rate of loss among the cadaver grafts, compared with the living relative donor grafts. Actuarial survival at eight years was 68 percent for living donor kidney recipients compared with 47 percent for cadaver kidney transplant recipients. Individual kidney transplant rejection after one year was almost always the result of chronic rejection. The different cyclosporine treatment regimens did not result in any differences in long-term survival. It is concluded that cyclosporine has improved the overall survival of kidney transplant recipients; however, chronic rejection is still a major problem. (Consumer Summary produced by Reliance Medical Information, Inc.)

Characteristics of tricuspid valve prolapse (TVP) on transthoracic echocardiography are not well defined. As tricuspid valve interventions are increasingly considered, information on the definition and clinical significance of TVP is needed.

Ultrasound enhancing agents (UEAs) are routinely used to improve transthoracic echocardiographic (TTE) image quality, yet anticipation of UEA need is a barrier to their use.

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ObjectiveThe Appropriate Use Criteria (AUC) has been used to identify individuals who are likely to benefit from percutaneous coronary intervention (PCI) for stable ischaemic heart disease. However, whether physicians reliably grade PCI appropriateness and whether AUC categories stratify symptomatic improvement in real-world practice are unclear.MethodsPatient-reported outcomes measures (PROMs) for angina (Seattle Angina Questionnaire (SAQ-7)), dyspnoea (Rose Dyspnea Scale (RDS)) and depression (Patient Health Questionnaire-2 (PHQ-2)) were collected on patients undergoing elective coronary angiography at an academic medical centre. Retrospectively, two physicians independently determined PCI appropriateness by the AUC criteria.ResultsInter-rater agreement on appropriateness was moderate (κ=0.48, 95% CI 0.32 to 0.63). Of PCI procedures evaluated, 57 (47.1%) were appropriate (A-PCI), 62 (51.2%) were maybe appropriate (MA-PCI) and 2 (1.6%) were rarely appropriate. At baseline, A-PCI compared with MA-PCI patients had worse RDS scores (2.0 vs 1.2, p=0.01). At 30 days, the change in SAQ-7 summary score was similar between groups (A-PCI vs MA-PCI, +27.1 vs +20.7, p=0.11). The mean change in RDS score was greater in A-PCI than MA-PCI (−1.0 vs −0.5, p for group by time interaction=0.03). PHQ-2 scores were similar and did not improve at 30 days.ConclusionIn patients undergoing PCI with PROMs collected before and 30 days after PCI, similar improvements in angina were observed regardless of appropriateness. Inter-rater agreement on PCI appropriateness was only moderate. Use of PROMs may improve reliability of physician assessments of PCI appropriateness.

The riverine transport and deposition of mud is the primary agent of landscape construction and evolution in many fluvial and coastal environments. Previous efforts exploring this process have raised uncertainty regarding the effects of hydrodynamic and chemical controls on the transport and deposition of mud, and thus the constructions of muddy coastal and upstream environments. As such, direct measurements are necessary to constrain the deposition of mud by river systems. Here, we combine laboratory evidence and a field investigation in the Mississippi River delta to explore the controls on the riverine transport and deposition of mud. We show that the flocculation of mud, with floc diameters greater than 10 μm, in freshwater is a ubiquitous phenomenon, causing the sedimentation of mud to be driven by changes in local hydrodynamics, and thus providing an explanation for how river systems construct landscapes through the deposition of mud in both coastal and upstream environments. Muddy landscapes are some of the most common and vital environments on Earth's surface, such as floodplains, deltas, and estuaries. Due to their small size, and thus easily suspendable nature, mud particles are thought to be extremely difficult to deposit under typical flow conditions in rivers. As such, the means by which rivers deposit mud has been the subject of much study and debate. Canonically, the deposition of cohesive sediment occurs as rivers approach the ocean, where increases in salinity induce the aggregation of clay and silt particles to form heavier floccules, or “flocs.” Recent studies have also explored the influence of organic material on mud aggregation. However, the means by which rivers are able to construct muddy landscapes upstream, in the absence of saline or organic‐rich water, remains uncertain. To address this discrepancy, we utilize a combination of laboratory evidence and a field investigation on the Mississippi River delta to show that all mud is transported as flocs, not as individual grains, and as such, the deposition of mud by river systems is controlled by the ability of the river flow to suspend existing mud flocs, and not by abrupt changes in water chemistry inducing flocculation in coastal regions. Flocculation of mud in water is a ubiquitous phenomenonSalinity may have little to no effect on mud floc size as rivers enter marine environmentsDeposition of flocculated mud in river systems is driven by changes in hydrodynamic stress Flocculation of mud in water is a ubiquitous phenomenon Salinity may have little to no effect on mud floc size as rivers enter marine environments Deposition of flocculated mud in river systems is driven by changes in hydrodynamic stress

•The value of echocardiography can be demonstrated via impact on patient outcomes.•Large, pooled echocardiographic data present unique challenges and opportunities.•Efforts to link imaging data across sites and to outcomes data are ongoing.

IMPORTANCE: The addition of a claims-based frailty metric to traditional comorbidity-based risk-adjustment models for acute myocardial infarction (AMI), heart failure (HF), and pneumonia improves the prediction of 30-day mortality and readmission. This may have important implications for hospitals that tend to care for frail populations and participate in Centers for Medicare & Medicaid Services value-based payment programs, which use these risk-adjusted metrics to determine reimbursement. OBJECTIVE: To determine whether the addition of frailty measures to traditional comorbidity-based risk-adjustment models improved prediction of outcomes for patients with AMI, HF, and pneumonia. DESIGN, SETTING, AND PARTICIPANTS: A nationwide cohort study included Medicare fee-for-service beneficiaries 65 years and older in the United States between January 1 and December 1, 2016. Analysis began August 2018. MAIN OUTCOMES AND MEASURES: Rates of mortality within 30 days of admission and 30 days of discharge, as well as 30-day readmission rates by frailty group. We evaluated the incremental effect of adding the Hospital Frailty Risk Score (HFRS) to current comorbidity-based risk-adjustment models for 30-day outcomes across all conditions. RESULTS: For 785 127 participants, there were 166 200 hospitalizations [21.2%] for AMI, 348 619 [44.4%] for HF, and 270 308 [34.4%] for pneumonia. The mean (SD) age at the time of hospitalization was 79.2 (8.9) years; 656 315 (83.6%) were white and 402 639 (51.3%) were women. The mean (SD) HFRS was 7.3 (7.4) for patients with AMI, 10.8 (8.3) for patients with HF, and 8.2 (5.7) for patients with pneumonia. Among patients hospitalized for AMI, an HFRS more than 15 (compared with an HFRS &lt;5) was associated with a higher risk of 30-day postadmission mortality (adjusted odds ratio [aOR], 3.6; 95% CI, 3.4-3.8), 30-day postdischarge mortality (aOR, 4.0; 95% CI, 3.7-4.3), and 30-day readmission (aOR, 3.0; 95% CI, 2.9-3.1) after multivariable adjustment for age, sex, race, and comorbidities. Similar patterns were observed for patients hospitalized with HF (30-day postadmission mortality: aOR, 3.5; 95% CI, 3.4-3.7; 30-day postdischarge mortality: aOR, 3.5; 95% CI, 3.3-3.6; and 30-day readmission: aOR, 2.9; 95% CI, 2.8-3.0) and among patients with pneumonia (30-day postadmission mortality: aOR, 2.5; 95% CI, 2.3-2.6; 30-day postdischarge mortality: aOR, 3.0; 95% CI, 2.9-3.2; and 30-day readmission: aOR, 2.8; 95% CI, 2.7-2.9). The addition of HFRS to traditional comorbidity-based risk-prediction models improved discrimination to predict outcomes for all 3 conditions. CONCLUSIONS AND RELEVANCE: Among Medicare fee-for-service beneficiaries, frailty as measured by the HFRS was associated with mortality and readmissions among patients hospitalized for AMI, HF, or pneumonia. The addition of HFRS to traditional comorbidity-based risk-prediction models improved the prediction of outcomes for all 3 conditions.

The role of basal septal hypertrophy (BSH) on preprocedural transthoracic echocardiography in transcatheter aortic valve replacement (TAVR) is unknown.

IMPORTANCE: Hospital outcomes for transcatheter aortic valve replacement (TAVR) may be dependent on the quality of evaluation, personnel, and procedural and postprocedural care common to patients undergoing cardiac surgery. OBJECTIVES: We sought to assess whether those hospitals with better patient outcomes for surgical aortic valve replacement (SAVR) subsequently achieved better TAVR outcomes after launching TAVR programs. DESIGN, SETTING, AND PARTICIPANTS: This national cohort included US patients 65 years and older. The analysis used the Centers for Medicare and Medicaid Services’ Medicare Provider and Review data collected between January 1, 2010, and September 29, 2015. Only hospitals performing at least 1 SAVR prior to September 1, 2011, and performing at least 1 TAVR after this date were included in the analysis. Data analysis was completed from June 2018 to August 2018. INTERVENTIONS: Isolated aortic valve replacements. MAIN OUTCOMES AND MEASURES: Hospital risk-adjusted 30-day mortality for SAVR in the pre-TAVR period was used as a surrogate for SAVR quality. Thirty-day and 1-year TAVR mortality rates were examined after stratification by quartile of baseline hospital risk-adjusted SAVR mortality. RESULTS: A total of 51 924 TAVR procedures were performed in 519 hospitals, of which 19 798 were performed at hospitals in quartile 1 (the lowest risk-adjusted SAVR mortality rate), 7663 were performed in quartile 2, 10 180 were performed in quartile 3, and 14 283 were performed in quartile 4 (the highest risk-adjusted SAVR mortality rate). Observed mortality rates at 30 days consistently increased with increasing baseline hospital SAVR risk-adjusted mortality (quartile 1, 917 patients [4.6%]; quartile 2, 381 [5.0%]; quartile 3, 521 [5.1%]; quartile 4, 800 [5.6%]; P &lt; .001). The same pattern was observed in 1-year mortality (quartile 1, 3359 [17.0%]; quartile 2, 1337 [17.5%]; quartile 3, 1852 [18.2%]; quartile 4, 2652 [18.6%]; P &lt; .001). After multivariable analysis, compared with the lowest quartile of SAVR mortality, undergoing TAVR at a hospital with higher baseline SAVR mortality continued to be associated with higher 30-day mortality (odds ratios: quartile 2, 1.02 [95% CI, 0.87-1.21]; quartile 3, 1.13 [95% CI, 1.02-1.26]; quartile 4, 1.23 [95% CI, 1.07-1.40]; P = .02) and 1-year mortality (hazard ratios: quartile 2, 1.04 [95% CI, 0.92-1.17]; quartile 3, 1.14 [95% CI, 1.02-1.28]; quartile 4, 1.16 [95% CI, 1.05-1.28]; P = .02). CONCLUSIONS AND RELEVANCE: Hospitals with higher SAVR mortality rates also had higher short-term and long-term TAVR mortality after initiating TAVR programs. Quality of cardiac surgical care may be associated with a hospital’s performance with new structural heart disease programs.

The common genetic variation at rs8004664 in the FOXN3gene is independently and significantly associated with fasting blood glucose, but not insulin, in non-diabetic humans. Recently, we reported that primary hepatocytes from rs8004664 hyperglycemia risk allele carriers have increased FOXN3 transcript and protein levels and liver-limited overexpression of human FOXN3, a transcriptional repressor that had not been implicated in metabolic regulation previously, increases fasting blood glucose in zebrafish. Here, we find that injection of glucagon into mice and adult zebrafish decreases liver Foxn3 protein and transcript levels. Zebrafish foxn3loss-of-function mutants have decreased fasting blood glucose, blood glucagon, liver gluconeogenic gene expression, and α cell mass. Conversely, liver-limited overexpression of foxn3increases α cell mass. Supporting these genetic findings in model organisms, non-diabetic rs8004664 risk allele carriers have decreased suppression of glucagon during oral glucose tolerance testing. By reciprocally regulating each other, liver FOXN3 and glucagon control fasting glucose.

The antidiabetic potential of glucagon receptor antagonism presents an opportunity for use in an insulin-centric clinical environment. To investigate the metabolic effects of glucagon receptor antagonism in type 2 diabetes, we treated Leprdb/dband Lepob/obmice with REMD 2.59, a human monoclonal antibody and competitive antagonist of the glucagon receptor. As expected, REMD 2.59 suppresses hepatic glucose production and improves glycemia. Surprisingly, it also enhances insulin action in both liver and skeletal muscle, coinciding with an increase in AMP-activated protein kinase (AMPK)-mediated lipid oxidation. Furthermore, weekly REMD 2.59 treatment over a period of months protects against diabetic cardiomyopathy. These functional improvements are not derived simply from correcting the systemic milieu; nondiabetic mice with cardiac-specific overexpression of lipoprotein lipase also show improvements in contractile function after REMD 2.59 treatment. These observations suggest that hyperglucagonemia enables lipotoxic conditions, allowing the development of insulin resistance and cardiac dysfunction during disease progression.

Peroxisome proliferator-activated receptor α (PPARα) is a nuclear hormone receptor that promotes fatty acid β-oxidation (FAO) and oxidative phosphorylation (OXPHOS). We and others have recently shown that PPARα and its target genes are downregulated, and FAO and OXPHOS are impaired in autosomal dominant polycystic kidney disease (ADPKD). However, whether PPARα and FAO/OXPHOS are causally linked to ADPKD progression is not entirely clear. We report that expression of PPARα and FAO/OXPHOS genes is downregulated, and in vivo β-oxidation rate of 3H-labeled triolein is reduced in Pkd1RC/RCmice, a slowly progressing orthologous model of ADPKD that closely mimics the human ADPKD phenotype. To evaluate the effects of upregulating PPARα, we conducted a 5-mo, randomized, preclinical trial by treating Pkd1RC/RCmice with fenofibrate, a clinically available PPARα agonist. Fenofibrate treatment resulted in increased expression of PPARα and FAO/OXPHOS genes, upregulation of peroxisomal and mitochondrial biogenesis markers, and higher β-oxidation rates in Pkd1RC/RCkidneys. MRI-assessed total kidney volume and total cyst volume, kidney-weight-to-body-weight ratio, cyst index, and serum creatinine levels were significantly reduced in fenofibrate-treated compared with untreated littermate Pkd1RC/RCmice. Moreover, fenofibrate treatment was associated with reduced kidney cyst proliferation and infiltration by inflammatory cells, including M2-like macrophages. Finally, fenofibrate treatment also reduced bile duct cyst number, cyst proliferation, and liver inflammation and fibrosis. In conclusion, our studies suggest that promoting PPARα activity to enhance mitochondrial metabolism may be a useful therapeutic strategy for ADPKD.

Aortic stenosis (AS) is the most common valvular heart disease in high-income countries. Adjusted for clinical confounders, the risk associated with increasing AS severity across the spectrum of AS severity remains uncertain.

The pathophysiological importance of the immunogenicity of damage‐associated molecular patterns (DAMPs) has been pinpointed by their identification as triggers of allograft rejection following release from dying cells, such as after ischemia–reperfusion injury. In cancers, however, this strong trigger of a specific immune response gives rise to the success of cancer immunotherapy. Here, we review the recently literature on the pathophysiological importance of DAMPrelease and discuss the implications of these processes for allograft rejection and cancer immunotherapy, revealing a striking mechanistic overlap. We conclude that these two fields share a common mechanistic basis of regulated necrosis and inflammation, the molecular characterization of which may be helpful for both oncologists and the transplant community. Damage‐associated molecular patterns are released from both allografts and cancer cells, thereby stimulating immune cells in an astonishingly similar fashion.

Facial transplantation is a life‐changing procedure for patients with severe composite facial defects. However, skin is the most immunogenic of all transplants, and better understanding of the immunological processes after facial transplantation is of paramount importance. Here, we describe six patients who underwent full facial transplantation at our institution, with a mean follow‐up of 2.7 years. Seum, peripheral blood mononuclear cells, and skin biopsy specimens were collected prospectively, and a detailed characterization of their immune response (51 time points) was performed, defining 47 immune cell subsets, 24 serum cytokines, anti‐HLAantibodies, and donor alloreactivity on each sample, producing 4269 data points. In a nonrejecting state, patients had a predominant T helper 2 cell phenotype in the blood. All patients developed at least one episode of acute cellular rejection, which was characterized by increases in interferon‐γ/interleukin‐17–producing cells in peripheral blood and in the allograft's skin. Serum monocyte chemotactic protein‐1 level was significantly increased during rejection compared with prerejection time points. None of the patients developed de novodonor‐specific antibodies, despite a fourfold expansion in T follicular helper cells at 1 year posttransplantation. In sum, facial transplantation is frequently complicated by a codominant interferon‐γ/interleukin‐17–mediated acute cellular rejection process. Despite that, medium‐term outcomes are promising with no evidence of de novodonor‐specific antibody development. In this study, the authors characterize the immune responses of six patients who underwent face transplantation and find that an increase in both IFN‐γ/IL‐17–producing cells in peripheral blood and in the allograft's skin with a concomitant peak in serum MCP‐1 levels and a reduction in circulating Th2 cells characterizes acute cellular rejection.

Identification of biomarkers that assess posttransplant risk is needed to improve long‐term outcomes following heart transplantation. The Clinical Trials in Organ Transplantation (CTOT)‐05 protocol was an observational, multicenter, cohort study of 200 heart transplant recipients followed for the first posttransplant year. The primary endpoint was a composite of death, graft loss/retransplantation, biopsy‐proven acute rejection (BPAR), and cardiac allograft vasculopathy (CAV) as defined by intravascular ultrasound (IVUS). We serially measured anti‐HLA‐ and auto‐antibodies, angiogenic proteins, peripheral blood allo‐reactivity, and peripheral blood gene expression patterns. We correlated assay results and clinical characteristics with the composite endpoint and its components. The composite endpoint was associated with older donor allografts (p < 0.03) and with recipient anti‐HLA antibody (p < 0.04). Recipient CMV‐negativity (regardless of donor status) was associated with BPAR (p < 0.001), and increases in plasma vascular endothelial growth factor‐C (OR 20; 95%CI:1.9–218) combined with decreases in endothelin‐1 (OR 0.14; 95%CI:0.02–0.97) associated with CAV. The remaining biomarkers showed no relationships with the study endpoints. While suboptimal endpoint definitions and lower than anticipated event rates were identified as potential study limitations, the results of this multicenter study do not yet support routine use of the selected assays as noninvasive approaches to detect BPAR and/or CAV following heart transplantation. In this observational, multicenter, cohort study of 200 heart transplant recipients, the investigators find that acute rejection and evidence of vasculopathy at 1 year posttransplant correlates with several epidemiological parameters, anti‐HLAantibodies and plasma angiogenesis‐related factors, but not with a panel of cellular and molecular biomarkers. See also Van Aelst et al on page 99.

Introduction:Frailty is associated with increased morbidity and mortality in patients undergoing left atrial appendage closure (LAAC). We compared the performance of two claims-based frailty measures in predicting adverse outcomes following LAAC.Methods:We identified patients 65 years and older who underwent LAAC between October 1, 2016 and December 31, 2019 in Medicare fee-for-service claims. Frailty was assessed using the previously validated Hospital Frailty Risk Score (HFRS) and Kim Claims-based Frailty Index (CFI). Patients were identified as frail based on HFRS ≥5 and CFI ≥0.25.Results:Of the 21,787 patients who underwent LAAC, frailty was identified in 45.6% by HFRS and 15.4% by CFI. There was modest agreement between the two frailty measures (kappa 0.25, Pearson’s correlation 0.62). After adjusting for age, sex, and comorbidities, frailty was associated with higher risk of 30-day mortality, 1-year mortality, 30-day readmission, long hospital stay, and short time at home (p<0.01 for all) regardless of the frailty instrument used. Model discrimination was similar between the HFRS and the CFI with fair discrimination of all outcomes (C-statistic 0.686 - 0.759). The addition of frailty to standard comorbidities significantly improved model performance to predict 1-year mortality, long hospital stay, and short time at home (Delong p-value <0.001).Conclusions:Despite significant variation in frailty detection and only modest agreement between the two frailty measures, frailty status was highly predictive of mortality, readmission, long hospital stay, and days at home. Future studies should focus on prospective evaluation of frailty in patients eligible for LAAC, which may further refine the relationship between frailty and adverse outcomes, and help inform shared decision-making in this population.

Introduction:Lower rates of transcatheter aortic valve implantation (TAVI) among Black individuals have been observed, the drivers of this disparity remain poorly understood. We studied the association between county-level racial segregation and rates of aortic stenosis (AS) diagnosis and management.Methods:We identified Black and white Medicare fee-for-service beneficiaries living in metropolitan areas between 2016 and 2019. Using the American Community Survey’s residential segregation index (SI), a measure of geographic distribution of Black and white residents ranging from 0 (complete integration) to 100 (complete segregation), we determined segregation in each beneficiaries’ county of residence. We calculated population-level rates of AS diagnosis and TAVI using validated ICD-10 codes. Using hierarchical modeling, we determined the association between racial segregation and rates of AS diagnosis, TAVI receipt, and 30-day mortality.Results:A total of 29,264,075 beneficiaries were included in the analysis. Living in a high-segregation county (SI>60) was associated with increased rates of AS diagnosis overall (adjusted OR 1.03 95%CI 1.02-1.03) but no difference in TAVI. However, among Black beneficiaries, increasing county-level segregation was associated with decreased rates of AS diagnosis and TAVI; the opposite association was observed among white beneficiaries (Figure 1). Among those with an AS diagnosis, the interaction between Black race and segregation, and lower rates of TAVI persisted (interaction p-value 0.003). Segregation and race were not independently associated with 30-day mortality.Conclusions:Living in a high-segregation county is independently associated with decreased population-level rates of AS diagnosis and receipt of TAVI for Black, but not white, individuals. Among Black people living in high-segregation counties, disparities in TAVI rates are associated with decreased AS diagnosis and access to TAVI.

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Acute rejection is the most common complication after vascularized composite allotransplantation (VCA). This review provides a state-of-the-art analysis of prevention, diagnosis and treatment of acute rejection episodes and highlights recent findings with the potential to improve patient care and enhance understanding of the underlying biologic processes.

The field of vascularized composite allograft (VCA) to achieve its full potential will require induction of tolerance. This review will introduce a new method of potential inducing tolerance in hand transplantation.

Multi‐potential hematopoietic stem cells rapidly infiltrate allogeneic and syngeneic transplants and sham surgery sites, representing an inflammatory rather than an adaptive immune response to allo‐antigen.

The growth of centers capable of performing percutaneous coronary intervention (PCI) has outpaced population growth despite declining incidence of myocardial infarction and prevalence of coronary artery disease, potentially increasing the proportion of operators falling below minimal yearly volume standards set by professional societies.

Short‐term treatment with alpha‐1‐antitrypsin in the peritransplant period prevents the otherwise inevitable failure of autologous islet cynomolgus transplants and enables indefinite survival in association with profound antiinflammatory, cytoprotective effects.

A standardized protocol for isolating RNA from urine sediments to perform quantitative PCR analyses of proinfl ammatory cytokines gene transcripts is developed and validated by six individual laboratories. See more in the CTOT series, pages 1859–1904.

Fc fusion proteins are a new emerging class of molecules for immune-targeted delivery of therapeutic proteins. Biophysical and bioanalytical characterization is critical for clinical development and delivery of therapeutic proteins. Here we report molecular and functional characterization of a recombinant human fusion protein Mutant IL-15/Fc. MutIL-15/Fc has a molecular weight of ∼95 kDa as determined by multiangle laser light scattering with online size exclusion chromatography and migrated at a faster rate (lower retention time) in gel filtration column. The kinetics of binding of MutIL-15/Fc to Fcγ receptor is best fitted in a bivalent modal with KD15 μM and KD29 μM determined by surface plasmon resonance (BIAcore). N-Glycoprofiling analysis revealed extensive glycosylation of MutIL-15/Fc. The Fc and IL-15 components in the MutIL-15/Fc are detected using the dual mode ELISA. The HT-2 cell proliferation inhibition assay is qualified as a quantitative in vitromarker functional assay. Molecular state changes associated with forced stress analyzed by SEC-MALS resulted in changes in bioactivity and Fc:Fcγ receptor interaction affinity. These data provide a systematic approach to molecular and functional characterization of the MutIL-15/Fc to establish product consistency and stability monitoring during storage and under drug delivery conditions.

Leptin, an adipose‐secreted hormone, links metabolism and immunity. Our aim was to determine whether leptin affects the alloimmune response. We used an allogeneic skin transplant model as a means to analyze the allograft immune response in Lepob/oband wild‐type mice. Leptin deficiency results in an increased frequency of Treg and Th2 cells and a prolonged graft survival. These effects of leptin deficiency indicate the importance of leptin and obesity in modulating the allograft immune responses. Our data suggest a possible explanation for the increased susceptibility of hyperleptinemic obese patients to acute and chronic graft rejection.

T-cell immunoglobulin mucin-3 (Tim-3) is expressed on pathogenic T cells, and its ligand galectin-9 (gal-9) is up-regulated in inflamed tissues. When Tim-3+T cells encounter high gal-9 levels, they are deleted. Tim-3 is up-regulated on activated T cells during GVHD. Inhibition of Tim-3/gal-9 binding by infusion of a Tim-3-Ig fusion protein or Tim-3−/−donor T cells increased T-cell proliferation and GVHD lethality. When the Tim-3/gal-9 pathway engagement was augmented using gal-9 transgenic recipients, GVHD lethality was slowed. Together, these data indicate a potential for modulating this pathway to reduce disease by increasing Tim-3 or gal-9 engagement. Paradoxically, when Tim-3/gal-9 was inhibited in the absence of donor T-regulatory cells (Tregs), GVHD was inhibited. GVHD reduction was associated with decreased colonic inflammatory cytokines as well as epithelial barrier destruction. CD25-depleted Tim-3−/−donor T cells underwent increased activation-induced cell death because of increased IFN-γ production. To our knowledge, these studies are the first to show that although the absence of Tim-3/gal-9 pathway interactions augments systemic GVHD, concurrent donor Treg depletion paradoxically and surprisingly inhibits GVHD. Thus, although donor Tregs typically inhibit GVHD, under some conditions, such Tregs actually may contribute to GVHD by reducing activation-induced T-cell death.

Preclinical studies in nonhuman primates (NHP) are particularly useful to evaluate the safety and efficacy of new therapeutic proteins developed for use in clinical transplantation. We hypothesized that a treatment that selectively destroys activated cytopathic donor reactive T cells while sparing resting and immunoregulatory T cells in a mouse model might also produce long‐term drug‐free engraftment and tolerance without the hazards of lymphopenia in the challenging nonhuman primate islet allograft model. Short‐term treatment with a regimen consisting of rapamycin, and IL‐2.Ig plus mutant antagonist‐type IL‐15.Ig cytolytic fusion proteins (triple therapy) posttransplantation results in prolonged, drug‐free engraftment of cynomolgus islet allografts. Moreover slow progressive loss of islet function in some recipients was not associated with obvious pathologic evidence of rejection.

The presence of alloreactive memory T cells is a major barrier for induction of tolerance in primates. In theory, delaying conditioning for tolerance induction until after organ transplantation could further decrease the efficacy of the regimen, since preexisting alloreactive memory T cells might be stimulated by the transplanted organ. Here, we show that such “delayed tolerance” can be induced in nonhuman primates through the mixed chimerism approach, if specific modifications to overcome/avoid donor‐specific memory T‐cell responses are provided. These modifications include adequate depletion of CD8+ memory T cells and timing of donor bone marrow administration to minimize levels of proinflammatory cytokines. Using this modified approach, mixed chimerism was induced successfully in 11 of 13 recipients of previously placed renal allografts and long‐term survival without immunosuppression could be achieved in at least 6 of these 11 animals.

It has been reported that rapamycin (RPM) can induce de novo conversion of the conventional CD4+Foxp3-T cells into CD4+Foxp3+regulatory T cells (iTregs) in transplantation setting. It is not clear whether RPM can similarly generate suppressor CD8+T cells to facilitate graft acceptance. In this study, we investigated the ability of short-term RPM treatment in promoting long-term acceptance (LTA) of MHC-mismatched skin allografts by generating a CD8+suppressor T-cell population. We found that CD4 knockout (KO) mice (in C57BL/6 background, H-2b) can promptly reject DBA/2 (H-2d) skin allografts with mean survival time (MST) being 13 days (p< 0.01). However, a short course RPM treatment in these animals induced LTA with graft MST longer than 100 days. Adoptive transfer of CD8+T cells from LTA group into recombination-activating gene 1 (Rag-1)-deficient mice provided donor-specific protection of DBA/2 skin grafts against cotransferred conventional CD8+T cells. Functionally active immunoregulatory CD8+T cells also resided in donor skin allografts. Eighteen percent of CD8+suppressor T cells expressed CD28 as measured by flow cytometry, and produced reduced levels of IFN-γ, IL-2, and IL-10 in comparison to CD8+effector T cells as measured by ELISA. It is unlikely that CD8+suppressor T cells mediated graft protection via IL-10, as IL-10/Fc fusion protein impaired RPM-induced LTA in CD4 KO mice. Our data supported the notion that RPM-induced suppressor CD8+T cells home to the allograft and exert donor-specific graft protection.

Within the immune system there is an exquisite ability to discriminate between “self” and “non-self” that is orchestrated by antigen-specific T lymphocytes. Genomic plasticity enables differentiation of naive CD4+ T lymphocytes into either regulatory cells (Treg) that express the transcription factor Foxp3 and actively prevent autoimmune self-destruction or effector cells (Teff) that attack and destroy their cognate target. An example of such plasticity is our recent discovery that leukemia inhibitory factor (LIF) supports Treg maturation in contrast to IL-6, which drives development of the pathogenic Th17 effector phenotype. This has revealed a LIF/IL6 axis in T cell development which can be exploited for modulation using targeted cytokine delivery. Here we demonstrate that LIF-loaded nanoparticles (NPs) directed to CD4+ T cells (i) oppose IL6-driven Th17 development; (ii) prolong survival of vascularized heart grafts in mice; and (iii) expand FOXP3+ CD4+ T cell numbers in a non-human primate model in vitro. In contrast, IL-6 loaded nanoparticles directed to CD4+ T cells increase Th17 development. Notably, nanoparticle-mediated delivery was demonstrated to be critical: unloaded nanoparticles and soluble LIF or IL-6 controls failed to recapitulate the efficacy of cytokine-loaded nanoparticles in induction and/or expansion of Foxp3+ cells or Th17 cells. Thus, this targeted nanoparticle approach is able to harness endogenous immune-regulatory pathways, providing a powerful new method to modulating T cell developmental plasticity in immune-mediated disease indications.

We have shown that CD39 and CD73 are coexpressed on the surface of murine CD4+Foxp3+regulatory T cells (Treg) and generate extracellular adenosine, contributing to Treg immunosuppressive activity. We now describe that CD39, independently of CD73, is expressed by a subset of blood‐derived human CD4+CD25+CD127lo Treg, defined by robust expression of Foxp3. A further distinct population of CD4+CD39+T lymphocytes can be identified, which do not express CD25 and FoxP3 and exhibit the memory effector cellular phenotype. Differential expression of CD25 and CD39 on circulating CD4+T cells distinguishes between Treg and pathogenic cellular populations that secrete proinflammatory cytokines such as IFNγ and IL‐17. These latter cell populations are increased, with a concomitant decrease in the CD4+CD25+CD39+Tregs, in the peripheral blood of patients with renal allograft rejection. We conclude that the ectonucleotidase CD39 is a useful and dynamic lymphocytes surface marker that can be used to identify different peripheral blood T cell‐populations to allow tracking of these in health and disease, as in renal allograft rejection.

Foxp3regulatory T cells (Tregs) express both ectoenzymes CD39 and CD73, which in tandem hydrolyze pericellular ATP into adenosine, an immunoinhibitory molecule that contributes to Treg suppressive function. Using Foxp3GFP knockin mice, we noted that the mouse CD4CD39T-cell pool contains two roughly equal size Foxp3and Foxp3?populations. While Foxp3CD39cells are CD73brightand are the bone fideTregs, Foxp3?CD39cells do not have suppressive activity and are CD44CD62L?CD25?CD73dim?, exhibiting memory cell phenotype. Functionally, CD39 expression on memory and Treg cells confers protection against ATP-induced apoptosis. Compared with Foxp3?CD39?naïve T cells, Foxp3?CD39cells freshly isolated from non-immunized mice express at rest significantly higher levels of mRNA for T-helper lineage-specific cytokines IFN-? (Th1), IL-4IL-10 (Th2), IL-17AF (Th17), as well as pro-inflammatory cytokines, and rapidly secrete these cytokines upon stimulation. Moreover, the presence of Foxp3?CD39cells inhibits TGF-? induction of Foxp3 in Foxp3?CD39?cells. Furthermore, when transferred in vivo, Foxp3?CD39cells rejected MHC-mismatched skin allografts in a much faster tempo than Foxp3?CD39?cells. Thus, besides Tregs, CD39 is also expressed on pre-existing memory T cells of Th1-, Th2- and Th17-types with heightened alloreactivity.

Within the immune system there is an exquisite ability to discriminate between "self" and "non-self" that is orchestrated by T lymphocytes. Discriminatory pathways guide differentiation of these lymphocytes into either regulatory (Treg) or effector (Teff) T cells, influenced by cues from the naïve T cell’s immediate micro-environment as it responds to cognate antigen. Reciprocal pathways may lead to commitment of naïve T cells into either the protective tolerance-promoting Treg, or to the pro-inflammatory Th17 effector phenotype. Primary activation of CD4+ lymphocytes stimulates their release of leukaemia inhibitory factor (LIF), and Treg continue to release LIF in response to antigen, implying a role for LIF in tolerance. In apparent contrast interleukin-6 (IL-6), although very closely related to LIF, promotes maturation of Th17 cells. Here we show that LIF and IL-6 behave as polar opposites in promoting commitment to the Treg and Th17 lineages. LIF augmented Foxp3 expression, the Treg lineage transcription factor, and suppressed IL-6-induced IL-17A protein release: in contrast IL-6 prevented expression of the LIF receptor subunit, gp190, at two levels, firstly by repressing gp190 transcription and secondly by inducing massive upregulation of axotrophin/MARCH-7, a novel E3 ubiquitin ligase involved in gp190 regulation. In vivo, anti-LIF treatment reduced donor-specific Treg in recipients of foreign spleen cells. Conversely, a single dose of biodegradable LIF nanoparticles, targeted to CD4, successfully manipulated the LIF/IL6 axis towards development of donor-specific Foxp3+Treg. The implications for therapy are profound, harnessing endogenous immune regulation by paracrine delivery of LIF to CD4+ cells in vivo.