iPSC-derived NK cells expressing high-affinity IgG Fc receptor fusion CD64/16A to mediate flexible, multi-tumor antigen targeting for lymphoma.

Introduction: NK cells can mediate tumor cell killing by natural cytotoxicity and by antibody-dependent cell-mediated cytotoxicity (ADCC), an anti-tumor mechanism mediated through the IgG Fc receptor CD16A (FcγRIIIA). CD16A polymorphisms conferring increased affinity for IgG positively correlate with clinical outcomes during monoclonal antibody therapy for lymphoma, linking increased binding affinity with increased therapeutic potential via ADCC. We have previously reported on the FcγR fusion CD64/16A consisting of the extracellular region of CD64 (FcγRI), a high-affinity Fc receptor normally expressed by myeloid cells, and the transmembrane/cytoplasmic regions of CD16A, to create a highly potent and novel activating fusion receptor. Here, we evaluate the therapeutic potential of engineered induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing CD64/16A as an "off-the-shelf", antibody-armed cellular therapy product with multi-antigen targeting potential. Methods: iNK cells were generated from iPSCs engineered to express CD64/16A and an interleukin (IL)-15/IL-15Rα fusion (IL-15RF) protein for cytokine independence. iNK cells and peripheral blood NK cells were expanded using irradiated K562-mbIL21-41BBL feeder cells to examine in in vitro and in vivo assays using the Raji lymphoma cell line. ADCC was evaluated in real-time by IncuCyte assays and using a xenograft mouse model with high circulating levels of human IgG. Results: Our data show that CD64/16A expressing iNK cells can mediate potent anti-tumor activity against human B cell lymphoma. In particular, (i) under suboptimal conditions, including low antibody concentrations and low effector-to-target ratios, iNK-CD64/16A cells mediate ADCC, (ii) iNK-CD64/16A cells can be pre-loaded with tumor-targeting antibodies (arming) to elicit ADCC, (iii) armed iNK-CD64/16A cells can be repurposed with additional antibodies to target new tumor antigens, and (iv) cryopreserved, armed iNK-CD64/16A are capable of sustained ADCC in a tumor xenograft model under saturating levels of human IgG. Discussion: iNK-CD64/16A cells allow for a flexible use of antibodies (antibody arming and antibody targeting), and an "off-the-shelf" platform for multi-antigen recognition to overcome limitations of adoptive cell therapies expressing fixed antigen receptors leading to cancer relapse due to antigen escape variants.

The impact of a care bundle with an emphasis on hemodynamic assessment on the short-term outcomes in neonates with congenital diaphragmatic hernia.

OBJECTIVE: To evaluate the short-term outcomes of implementing a care bundle emphasizing frequent hemodynamic assessments by echocardiography in neonates with congenital diaphragmatic hernia (CDH). STUDY DESIGN: This was a retrospective cohort study of infants with CDH admitted to a quaternary perinatal unit from January 2013 to March 2021. The primary composite outcome was defined as mortality or use of extracorporeal membrane oxygenation or need for respiratory support at discharge. RESULTS: We identified 37 and 20 CDH infants in Epoch I and II, respectively. More patch repairs (50% vs. 21.9%, p = 0.035) and echocardiograms (6[4-8] vs. 1[0-5], p = 0.003) were performed in Epoch II. While there were no differences in the primary outcome, there was a reduction in mortality in Epoch II (0% vs. 27%, p = 0.01). CONCLUSION: With the implementation of a CDH care bundle with an emphasis on hemodynamic assessment, we demonstrated a significant reduction in mortality.

iPSC-derived natural killer cells expressing the FcγR fusion CD64/16A can be armed with antibodies for multitumor antigen targeting.

BACKGROUND: Antibody therapies can direct natural killer (NK) cells to tumor cells, tumor-associated cells, and suppressive immune cells to mediate antibody-dependent cell-mediated cytotoxicity (ADCC). This antigen-specific effector function of human NK cells is mediated by the IgG Fc receptor CD16A (FcγRIIIA). Preclinical and clinical studies indicate that increasing the binding affinity and avidity of CD16A for antibodies improves the therapeutic potential of ADCC. CD64 (FcγRI), expressed by myeloid cells but not NK cells, is the only high affinity IgG Fc receptor and is uniquely capable of stably binding to free monomeric IgG as a physiological function. We have reported on the generation of the FcγR fusion CD64/16A, consisting of the extracellular region of CD64 and the transmembrane and cytoplasmic regions from CD16A, retaining its signaling and cellular activity. Here, we generated induced pluripotent stem cell (iPSC)-derived NK (iNK) cells expressing CD64/16A as a potential adoptive NK cell therapy for increased ADCC potency. METHODS: iPSCs were engineered to express CD64/16A as well as an interleukin (IL)-15/IL-15Rα fusion (IL-15RF) protein and differentiated into iNK cells. iNK cells and peripheral blood NK cells were expanded using irradiated K562-mbIL21-41BBL feeder cells and examined. NK cells, ovarian tumor cell lines, and therapeutic monoclonal antibodies were used to assess ADCC in vitro, performed by a DELFIA EuTDA assay or in real-time by IncuCyte assays, and in vivo. For the latter, we developed a xenograft mouse model with high circulating levels of human IgG for more physiological relevance. RESULTS: We demonstrate that (1) iNK-CD64/16A cells after expansion or thaw from cryopreservation can be coupled to therapeutic antibodies, creating armed iNK cells; (2) antibody-armed iNK-CD64/16A cells can be redirected by added antibodies to target new tumor antigens, highlighting additional potential of these cells; (3) cytokine-autonomous activity by iNK-CD64/16A cells engineered to express IL-15RF; and that (4) antibody-armed iNK-CD64/16A cells thawed from cryopreservation are capable of sustained and robust ADCC in vitro and in vivo, as determined by using a modified tumor xenograft model with high levels of competing human IgG. CONCLUSIONS: iNK cells expressing CD64/16A provide an off-the-shelf multiantigen targeting platform to address tumor heterogeneity and mitigate antigen escape.

Targeted neonatal echocardiography for patent ductus arteriosus in neonates reduces the surgical ligation rate without affecting healthcare outcomes.

Background: Surgical ligation of patent ductus arteriosus (PDA) can be associated with long-term morbidity and adverse outcomes in neonates. Targeted neonatal echocardiography (TNE) has been increasingly used to improve the hemodynamic management. We aimed to evaluate the preoperative assessment impacts of the hemodynamic significance of PDA using TNE on PDA ligation rates and neonatal outcomes. Methods: This observational study included preterm infants who underwent PDA ligation during two epochs (Epoch I: January 2013 to December 2014; Epoch II: January 2015 to June 2016). During Epoch II, a comprehensive TNE assessment was performed preoperatively to evaluate the hemodynamic significance of PDA. Primary outcome was the incidence of PDA ligation. Secondary outcomes included the incidence of postoperative cardiorespiratory instabilities, individual morbidities, and the composite outcome of death. Results: A total of 69 neonates underwent PDA ligation. No difference in baseline demographics was found between the epochs. The incidence of PDA ligation in very low birth weight (VLBW) infants was lower during Epoch II than Epoch I [7.5% vs. 14.6%, rate ratio =0.51 (95% confidence interval =0.30-0.88)]. No differences were observed between epochs in the proportion of VLBW infants who developed post-operative hypotension or oxygenation failure. The composite outcome of death or major morbidity did not significantly differ between Epoch I and Epoch II (91.1% vs. 94.1%, P=1.000). Conclusions: Incorporating TNE into a standardized hemodynamic assessment program, we demonstrated a 49% reduction in PDA ligation rate without any increase in postoperative cardiopulmonary instability or short-term neonatal morbidities in a cohort of VLBW infants.

A Canadian, retrospective, multicenter experience with selexipag for a heterogeneous group of pediatric pulmonary hypertension patients.

Introduction: Selexipag, an oral nonprostanoid prostaglandin receptor agonist, has led to reduced morbidity and mortality in adults with pulmonary arterial hypertension (PAH). While the adult literature has been extrapolated to suggest selexipag as an oral treatment for severe pediatric pulmonary hypertension (PH), longitudinal, multicenter data on the benefits of selexipag in this population are lacking. The purpose of this study is to present a longitudinal, multicentre experience with selexipag in a relatively large cohort of pediatric PH patients and add to the existing selexipag literature. Materials and methods: We performed a retrospective, multicenter review describing the clinical outcomes of pediatric PH patients receiving selexipag in addition to standard oral pulmonary vasodilator therapy across three Canadian centers between January 2005 and June 2021. Results: Twenty-four pediatric patients (fifteen female) with a mean age of 9.7 (range 2.0-15.5) years were included. Of this cohort, eighteen (75.0%) were in group 1, one (4.2%) was in group 2, four (16.7%) were in group 3, and one (4.2%) was in group 4. Twenty-two (91.7%) patients were on dual PH therapy after six months. Dosing was targeted to achieve 20-30 mcg/kg/dose orally every twelve hours. Median dose after twelve months was 30 mcg/kg/dose. Twelve months following selexipag initiation, median decreases of 0.2 cm in tricuspid annular plane systolic excursion, 3.5 mmHg in right-ventricular systolic pressure, and 6.1 mmHg in mean pulmonary arterial pressure were observed; none of these changes were statistically significant. Three patients died, one clinically deteriorated and required admission to a pediatric intensive care unit, ten had gastrointestinal symptoms, and three had flushing. Conclusion: Selexipag appears to be a safe and effective adjunctive therapy for pediatric PH patients and has a tolerable adverse effect profile aside from gastrointestinal disturbances. Additional prospective studies of changes in hemodynamics and functional classification over a longer period and with a larger sample are needed. Future research should aim to identify subgroups that stand to benefit from the addition of selexipag as well as optimal timing and dosing for the pediatric population.

Human JAK1 gain of function causes dysregulated myelopoeisis and severe allergic inflammation.

Primary atopic disorders are a group of inborn errors of immunity that skew the immune system toward severe allergic disease. Defining the biology underlying these extreme monogenic phenotypes reveals shared mechanisms underlying common polygenic allergic disease and identifies potential drug targets. Germline gain-of-function (GOF) variants in JAK1 are a cause of severe atopy and eosinophilia. Modeling the JAK1GOF (p.A634D) variant in both zebrafish and human induced pluripotent stem cells (iPSCs) revealed enhanced myelopoiesis. RNA-Seq of JAK1GOF human whole blood, iPSCs, and transgenic zebrafish revealed a shared core set of dysregulated genes involved in IL-4, IL-13, and IFN signaling. Immunophenotypic and transcriptomic analysis of patients carrying a JAK1GOF variant revealed marked Th cell skewing. Moreover, long-term ruxolitinib treatment of 2 children carrying the JAK1GOF (p.A634D) variant remarkably improved their growth, eosinophilia, and clinical features of allergic inflammation. This work highlights the role of JAK1 signaling in atopic immune dysregulation and the clinical impact of JAK1/2 inhibition in treating eosinophilic and allergic disease.

Patterns of Early Coronary Artery Changes in Pediatric Heart Transplant Recipients Detected Using Optical Coherence Tomography.

BACKGROUND: Cardiac allograft vasculopathy, the leading cause of graft failure in pediatric heart transplant recipients, is characterized by diffuse and concentric coronary intimal thickening. Early treatment yields better outcomes. While coronary angiography is the standard for cardiac allograft vasculopathy screening and diagnosis, it only identifies luminal narrowing, which occurs in more severe disease. Coronary optical coherence tomography (OCT) is a high-definition intravascular imaging modality that may offer earlier diagnosis. We used OCT to investigate coronary intimal thickening in pediatric transplant recipients and examined its (1) location (ie, vessel type and location) and (2) nature (ie, characteristics of cross-sectional and longitudinal thickening). METHODS: Sites collected coronary angiography and OCT data from participants (N=258 vessel segments from 73 individuals; median age: 11.5 years [8.4-15.3]; 55% male). Images were collected from the left anterior descending, left circumflex, and right coronary arteries, and location (ie, proximal, middle, and distal) were classified using coronary angiography. RESULTS: OCT identified 32 vessel segments meeting criteria for significant thickening, 88% of which were angiographically silent. Longitudinal thickening was segmental rather than global in 88%, and cross-sectional thickening was 48% eccentric and 52% concentric. Intimal thickening prevalence and severity measures did not consistently differ between coronary artery type (P=1.000) or location (P=0.248) but increased with time since transplant and age at transplant and OCT procedure. CONCLUSIONS: In pediatric transplant recipients, we observed a surprisingly high prevalence of segmental and eccentric intimal thickening. Insights from intravascular imaging suggest these patterns of coronary vascular changes may precede overt cardiac allograft vasculopathy. Identifying early changes may offer opportunity for enhanced surveillance and earlier intervention.

Utility and Access to 3-Dimensional Printing in the Context of Congenital Heart Disease: An International Physician Survey Study.

BACKGROUND: Three-dimensional (3D) printing is a new technology capable of producing patient-specific 3D cardiac models. METHODS: A cross-sectional survey of pediatric cardiologists was conducted. Members of the Canadian Pediatric Cardiology Association and Congenital Cardiac Interventional Study Consortium were invited to participate. A questionnaire was distributed using Research Electronic Data Capture between May and September 2019. Results were analyzed using descriptive statistics, Fisher exact test, and odds ratio. RESULTS: A total of 71 pediatric cardiologists responded. Some 85% (60/71) agreed that patient-specific 3D printed cardiac models are a beneficial tool in treating children with congenital heart disease (CHD); 80% of those (48/60) believe 3D models facilitate communication with colleagues; 49% (35/71) of respondents had access to 3D printing technology; and 77% (27/35) of those were using models for clinical care. Access differed according to geographic location (P = 0.004). Of respondents, Americans were 5.5 times more likely (confidence interval, 1.6-19.2) than Canadians to have access to 3D printing technology. The primary reason for lack of access was financial barriers (50%, 18/36). In clinical practice, surgical planning is the primary use of models (96%, 26/27), followed by interventional catheterization planning (52%, 14/27). Double outlet right ventricle was the most commonly modelled lesion (70%, 19/27). CONCLUSION: 3D printing is a new technology that is beneficial in the care of children with CHD. Access to 3D printing varies by geographic location. In pediatric cardiology, 3D models are primarily used for procedural planning for CHD lesions with complex 3D spatial relationships.

CONTEXTE: L'impression en trois dimensions (3D) est une nouvelle technologie permettant de produire des modèles cardiaques 3D sur mesure pour chaque patient. MÉTHODOLOGIE: Une enquête transversale a été menée auprès de cardiologues-pédiatres. Les membres de l'Association canadienne de cardiologie pédiatrique et du Congenital Cardiac Interventional Study Consortium ont été invités à y participer. À cette fin, un questionnaire a été diffusé au moyen de l'outil REDCap (Research Electronic Data Capture) de mai à septembre 2019. Les résultats ont été analysés au moyen de techniques de statistique descriptive, du test exact de Fisher et du rapport de cotes. RÉSULTATS: Au total, 71 cardiologues-pédiatres ont répondu au questionnaire. Environ 85 % (60/71) des répondants convenaient que les modèles cardiaques personnalisés à chaque patient et produits par impression 3D sont utiles pour traiter les enfants atteints d'une cardiopathie congénitale; de ce nombre, 80 % (48/60) estimaient que les modèles 3D facilitent la communication entre collègues; 49 % (35/71) avaient accès à la technologie d'impression 3D et, parmi eux, 77 % (27/35) se servaient de modèles pour prodiguer des soins cliniques. L'accès variait selon l'emplacement géographique (p = 0,004). Parmi les répondants, les médecins situés aux États-Unis étaient 5,5 fois plus susceptibles (intervalle de confiance : 1,6-19,2) que les médecins canadiens d'avoir accès à la technologie d'impression 3D. Les ressources financières constituaient le principal obstacle à l'accès à cette technologie (50 %, 18/36). Dans la pratique clinique, les modèles sont surtout utilisés pour planifier les interventions chirurgicales (96 %, 26/27) et le cathétérisme interventionnel (52 %, 14/27). Le ventricule droit à double issue était particulièrement modélisé (70 %, 19/27). CONCLUSION: L'impression 3D est une nouvelle technologie utile pour soigner les enfants présentant une cardiopathie congénitale. L'accès à cette technologie varie selon l'emplacement géographique. En cardiologie-pédiatrie, les modèles 3D sont surtout utilisés pour planifier les interventions relatives à des cardiopathies congénitales complexes sur le plan tridimensionnel.

Utility of 3D printed cardiac models in congenital heart disease: a scoping review.

OBJECTIVE: Three-dimensional printing (3DP) is a novel technology with applications in healthcare, particularly for congenital heart disease (CHD). We sought to explore the spectrum of use of 3D printed CHD models (3D-CM) and identify knowledge gaps within the published body of literature to guide future research. METHODS: We conducted a scoping review targeting published literature on the use of 3D-CMs. The databases of MEDLINE, EMBASE and Web of Science were searched from their inception until 19 July 2019. Inclusion criteria were primary research; studies reporting use of 3D-CMs; and human subjects. Exclusion criteria were studies where 3D-CMs were generated for proof of concept but not used; and studies focused on bioprinting or computational 3D-CMs. Studies were assessed for inclusion and data were extracted from eligible articles in duplicate. RESULTS: The search returned 648 results. Following assessment, 79 articles were included in the final qualitative synthesis. The majority (66%) of studies are case reports or series. 15% reported use of a control group. Three main areas of utilisation are for (1) surgical and interventional cardiology procedural planning (n=62), (2) simulation (n=25), and (3) education for medical personnel or patients and their families (n=17). Multiple studies used 3D-CMs for more than one of these areas. CONCLUSIONS: 3DP for CHD is a new technology with an evolving literature base. Most of the published literature are experiential reports as opposed to manuscripts on scientifically robust studies. Our study has identified gaps in the literature and addressed priority areas for future research.

Pulmonary artery wall thickness in children with Fontan physiology: an optical coherence tomography case control study.

INTRODUCTION: Failure of the Fontan circulation is not a well-understood clinical phenomena.For some patients, a gradual increase in pulmonary vascular resistance (PVR) and structural changes in the pulmonary artery may be an important causative factor. To further investigate this issue, we employed optical coherence tomography (OCT) to evaluate structural changes within the pulmonary arteries of Fontan patients and compared to those with a normal pulmonary circulation. MATERIALS AND METHODS: Pulmonary artery OCT was performed, without complications, in 12 Fontan and 11 control patients. Wall thickness and wall:vessel cross-sectional area (CSA) ratio were calculated after image acquisition, using digital planimetry. RESULTS: There was no difference in wall thickness between both groups. Median wall thickness for Fontan patients was 0.12 mm (IQR, 0.10-0.14) and for controls was 0.11 mm (IQR, 0.10-0.12; p = 0.62). Wall:vessel CSA ratio for Fontan patients was 0.13 (IQR, 0.12-0.16) and for controls was 0.13 (IQR, 0.11-0.15) (p = 0.73). There was no association between wall thickness and ventricle morphology, age at catheterisation, age at Fontan, years since Fontan completion, pulmonary artery pressure, and PVR. The vessel media was more readily visualised in control patients. DISCUSSION: OCT of the pulmonary arteries in Fontan patients is safe and feasible. Our OCT findings suggest that during childhood, pulmonary artery wall dimensions are normal in Fontan children with reassuring hemodynamics. Further evaluation of Fontan patients with abnormal hemodynamics and serial evaluation into adulthood are required to conclude on the utility of OCT for identifying early pulmonary artery structural changes.

Physiological Responses to Exercise in Pediatric Heart Transplant Recipients.

INTRODUCTION: Pediatric heart transplant (HTx) recipients have reduced exercise capacity typically two-thirds of predicted values, the mechanisms of which are not fully understood. We sought to assess the cardiorespiratory responses to progressive exercise in HTx relative to controls matched for age, sex, body size, and work rate. METHODS: Fourteen HTx recipients and matched controls underwent exercise stress echocardiography on a semisupine cycle ergometer. Hemodynamics, left ventricular (LV) dimensions, and volumes were obtained and indexed to body surface area. Oxygen consumption (V˙O2) was measured, and arteriovenous oxygen difference was estimated using the Fick Principle. RESULTS: At rest, LV mass index (P = 0.03) and volumes (P < 0.001) were significantly smaller in HTx, whereas wall thickness (P < 0.01) and LV mass-to-volume ratio (P = 0.01) were greater. Differences in LV dimensions and stroke volume persisted throughout exercise, but the pattern of response was similar between groups as HR increased. As exercise progressed, heart rate and cardiac index increased to a lesser extent in HTx. Despite this, V˙O2 was similar (P = 0.82) at equivalent work rates as HTx had a greater change in arteriovenous oxygen difference (P < 0.01). CONCLUSIONS: When matched for work rate, HTx had similar metabolic responses to controls despite having smaller LV chambers and an attenuated increase in hemodynamic responses. These findings suggest that HTx may increase peripheral O2 extraction as a compensatory mechanism in response to reduced cardiovascular function.

Optical Coherence Tomography for the Early Detection of Coronary Vascular Changes in Children and Adolescents After Cardiac Transplantation: Findings From the International Pediatric OCT Registry.

OBJECTIVES: This study sought to describe the initial findings from the International Pediatric Optical Coherence Tomography (OCT) registry in pediatric heart transplant recipients. BACKGROUND: Cardiac allograft vasculopathy (CAV) is a common cause of late graft failure and mortality in pediatric heart transplant recipients. Early diagnosis may improve outcomes. OCT is a high-resolution intravascular imaging technique that has the potential to identify CAV earlier than angiography. METHODS: OCT and angiography of the coronary arteries were performed in pediatric heart transplant recipients at participating centers. Demographics, clinical data, medications, episodes of rejection, and angiographically confirmed CAV were collected for each case. OCT and angiography images were analyzed in a central core imaging laboratory. Intimal thickness and intima/media cross sectional area (I/M CSA) ratios were calculated for each case. Intimal thickness ≥0.25 mm was defined as abnormal and ≥0.4 mm as severe intima thickening. I/M CSA ratio of ≥1 was defined as abnormal. OCT findings were compared to angiographic findings for each case. RESULTS: Across 3 centers, 110 cases were analyzed from 76 patients. Intimal thickening was present in 26 of 110 cases. Eleven of these cases had severe intima thickening (≥0.4 mm) and notably, angiography results were normal in 8 cases. All 5 cases with a median I/M CSA ratio of ≥2 had normal angiography. The maximal intima thickness was ≥0.25 mm in 24% and ≥0.4 mm in 10% of cases. Median I/M CSA ratio was ≥1 for 80% of cases. I/M CSA ratio was significantly higher in cases with concurrent CAV (p = 0.03). Maximal intima thickness was significantly greater in cases with current or previous rejection (p = 0.01). I/M CSA ratio was significantly lower in patients treated with statins (p = 0.01). OCT findings alone prompted a change to medical management in 17% of cases. CONCLUSIONS: OCT provides important insights into coronary vascular changes not detected by angiography in pediatric transplant recipients. The use of OCT for pediatric heart transplant recipients should be further investigated, given its potential to impact the management of CAV.

Coronary artery intimal thickening and ventricular dynamics in pediatric heart transplant recipients.

OBJECTIVE: Pediatric heart transplant recipients are at risk of posttransplant coronary artery disease known as cardiac allograft vasculopathy (CAV), and also may develop diastolic dysfunction. As CAV begins with a process of progressive intimal thickening, these occult diffuse changes may be detected using optical coherence tomography (OCT). We hypothesized that the development of CAV, as identified via OCT, may be a mechanism of declining ventricular function. Accordingly, the purpose of this study was to assess coronary artery intimal thickening and LV strain in children who have undergone heart transplantation. METHODS: In 17 children, we analyzed OCT images for coronary intima and media thickness, and cross-sectional area (CSA). We also performed speckle tracking imaging (STI) of the LV to determine longitudinal strain and strain rate, in addition to standard echocardiographic measures. RESULTS: Longitudinal diastolic strain rate was associated with maximum intima thickness (r = -.497, P = .042), intima CSA, (r = -.489, P = .047), maximum media thickness (r = -.503, P = .039), and media CSA (r = -.614, P = .009). The intima maximum thickness, intima/media, and intima/lumen ratios were associated with stroke volume index (Std. ß = -0.487, P = .023 and Std. ß = -0.488, P = .022, respectively). CONCLUSIONS: These findings suggest coronary artery intimal thickening may be mechanistically linked to changes in ventricular function following cardiac transplantation.

Intimal thickening at coronary bifurcations in pediatric heart transplant recipients.

Heart transplant recipients are at increased risk for atherosclerosis and cardiac allograft vasculopathy, both initially presenting as intimal thickening. We aimed to determine the presence, extent, and anatomical characteristics of intimal thickness at coronary bifurcations in children using OCT. We measured the intimal thickness of coronary arteries in pediatric transplant recipients using OCT during routine cardiac catheterization. Intimal thickening was defined as (i) a percent change in contralateral intimal thickness greater than 50% when comparing the thickness at the bifurcation to the baseline thickness, and (ii) greater than 0.1 mm. We evaluated 153 unique coronary bifurcations in 31 children (58% boys, median 12.7 years). Intimal thickening was almost exclusively observed in the left coronary system (22 of 67 bifurcations) and rare in the right coronary system (2 of 86 bifurcations; P < .001). There was a positive association between the relative size of the side branch and contralateral intimal thickening at coronary bifurcations (P = .009). Intimal thickening at coronary bifurcations is already present in the left coronary system in many pediatric transplant recipients. The correlation between intimal thickening and side branch size suggests that low shear stress and oscillating shear stress may have an important role in the development of intimal thickening at coronary bifurcations.

Jellyfish-Like Accessory Mitral Valve Tissue Causing Near-Collapse in a Young Child.

Accessory mitral valve tissue (AMVT) causing left ventricular outflow tract obstruction (LVOTO) is rare. We report a case of AMVT causing severe LVOTO resulting in acutely progressive symptoms of near-collapse. Urgent surgical resection eliminated the patient's life-threatening symptoms. AMVT should be considered among potential LVOTO diagnoses, and early surgical intervention may be required.

A Systematic Review of Infective Endocarditis in Patients With Bovine Jugular Vein Valves Compared With Other Valve Types.

OBJECTIVES: The aim of this study was to systematically evaluate the incidence of infective endocarditis (IE) in right ventricle-to-pulmonary artery conduits and valves, comparing bovine jugular vein (BJV) valves with all others. BACKGROUND: Recent evidence suggests that the incidence of IE is higher in patients with congenital heart disease who have undergone implantation of BJV valves in the pulmonary position compared with other valves. METHODS: Systematic searches of published research were conducted using electronic databases (MEDLINE, Embase, and CINAHL) and citations cross-referenced current to April 2016. Included studies met the following criteria: patients had undergone right ventricle-to-pulmonary artery conduit or percutaneous pulmonary valve implantation, and investigators reported on the type of conduit or valve implanted, method of intervention (surgery or catheter based), IE incidence, and follow-up time. RESULTS: Fifty studies (Levels of Evidence: 2 to 4) were identified involving 7,063 patients. The median cumulative incidence of IE was higher for BJV compared with other valves (5.4% vs. 1.2%; p < 0.0001) during a median follow-up period of 24.0 and 35.5 months, respectively (p = 0.03). For patients with BJV valves, the incidence of IE was not different between surgical and catheter-based valve implantation (p = 0.83). CONCLUSIONS: There was a higher incidence of endocarditis with BJV valves than other types of right ventricle-to-pulmonary artery conduits. There was no difference in the incidence of endocarditis between catheter-based bovine valves and surgically implanted bovine valves, suggesting that the substrate for future infection is related to the tissue rather than the method of implantation.

Outcomes of Radiofrequency Perforation for Pulmonary Atresia and Intact Ventricular Septum: A Single-Centre Experience.

Percutaneous radiofrequency perforation (RFP) of the pulmonary valve is used as a primary therapy in neonates with pulmonary atresia and intact ventricular septum (PAIVS). We sought to determine the safety and efficacy of RFP for PAIVS in a single center and assess the pre-intervention anatomical parameters associated with a biventricular outcome. We retrospectively reviewed all cases of PAIVS treated with RFP at a single center from 1999 through 2012. We collected baseline imaging data, technical aspects of the procedure, adverse events and outcomes. RFP was attempted in 18 patients with 17 successful procedures. There was no mortality; one patient had an acute complication requiring surgical intervention. All were alive at the most recent follow-up (median 4.9 years; IQR = 2.0-6.8 years), 12/17 (71%) had a biventricular circulation, 2/17 (12%) had a 1½ ventricle repair, 2/17 (12%) had a univentricular repair and 1/17 was lost to follow-up. A biventricular outcome in patients with PAIVS was associated with the pre-intervention tricuspid valve/mitral valve (TV/MV) ratio and tricuspid valve (TV) z-score. The median TV/MV ratio for patients who underwent a biventricular repair and a non-biventricular repair was 0.82 (IQR = 0.71-0.90) and 0.59 (IQR = 0.39-0.76), P = 0.036, respectively. The median TV z-scores were -3.2 [(-4.9 to -2.6), and -6.8 (-9.7 to -4.8] P = 0.036 for the biventricular and non-biventricular groups, respectively. RFP is a safe primary therapy for PAIVS. With appropriate patient selection, RFP will often result in a biventricular circulation. Both the TV/MV and TV z-score were found to be a predictor of a biventricular outcome in our cohort.

Type I IFN Signaling Is Dispensable during Secondary Viral Infection.

Innate immune responses in general, and type I interferons (T1IFNs) in particular, play an important and often essential role during primary viral infections, by directly combatting the virus and by maximizing the primary adaptive immune response. Several studies have suggested that T1IFNs also contribute very substantially to the secondary (recall) response; they are thought (i) to be required to drive the early attrition of memory T cells, (ii) to support the subsequent expansion of surviving virus-specific memory cells, and (iii) to assist in the suppression and clearance of the infectious agent. However, many of these observations were predicated upon models in which T1IFN signaling was interrupted prior to a primary immune response, raising the possibility that the resulting memory cells might be intrinsically abnormal. We have directly addressed this by using an inducible-Cre model system in which the host remains genetically-intact during the primary response to infection, and in which T1IFN signaling can be effectively ablated prior to secondary viral challenge. We report that, in stark contrast to primary infection, T1IFN signaling is not required during the recall response. IFNαßR-deficient memory CD8+ and CD4+ memory T cells undergo attrition and expansion with kinetics that are indistinguishable from those of receptor-sufficient cells. Moreover, even in the absence of functional T1IFN signaling, the host's immune capacity to rapidly suppress, and then to eradicate, a secondary infection remains intact. Thus, this study shows that T1IFN signaling is dispensable during the recall response to a virus infection. Moreover, two broader implications may be drawn. First, a T cell's requirement for a cytokine is highly dependent on the cell's maturation / differentiation status. Consequently, second, these data underscore the importance of evaluating a gene's impact by modulating its expression or function in a temporally-controllable manner.

TCR independent suppression of CD8(+) T cell cytokine production mediated by IFNγ in vivo.

CD8(+) memory T cells produce IFNγ within hours of secondary infection, but this is quickly terminated in vivo despite the presence of stimulatory viral antigen, suggesting that active suppression occurs. Herein, we investigated the in vivo effector function of CD8(+) memory T cells during successive encounters with viral antigen. CD8(+) T cells in immune mice receiving prior viral or peptide challenge failed to reproduce IFNγ during LCMV rechallenge. Surprisingly, this refractory state was induced even in memory cells that had not encountered their cognate antigen, indicating that the silencing of CD8(+) T cell responses is TCR-independent. Direct injection of IFNγ also suppressed the ability of virus-specific memory cells to respond to subsequent viral challenge. We propose the existence of a negative feedback loop whereby IFNγ, produced by memory CD8(+) T cells to combat viral challenge, acts - directly or indirectly - to limit its further production.