Integrated multi-omic characterization of congenital heart disease.

The heart, the first organ to develop in the embryo, undergoes complex morphogenesis that when defective results in congenital heart disease (CHD). With current therapies, more than 90% of patients with CHD survive into adulthood, but many suffer premature death from heart failure and non-cardiac causes1. Here, to gain insight into this disease progression, we performed single-nucleus RNA sequencing on 157,273 nuclei from control hearts and hearts from patients with CHD, including those with hypoplastic left heart syndrome (HLHS) and tetralogy of Fallot, two common forms of cyanotic CHD lesions, as well as dilated and hypertrophic cardiomyopathies. We observed CHD-specific cell states in cardiomyocytes, which showed evidence of insulin resistance and increased expression of genes associated with FOXO signalling and CRIM1. Cardiac fibroblasts in HLHS were enriched in a low-Hippo and high-YAP cell state characteristic of activated cardiac fibroblasts. Imaging mass cytometry uncovered a spatially resolved perivascular microenvironment consistent with an immunodeficient state in CHD. Peripheral immune cell profiling suggested deficient monocytic immunity in CHD, in agreement with the predilection in CHD to infection and cancer2. Our comprehensive phenotyping of CHD provides a roadmap towards future personalized treatments for CHD.

Congenital heart disease linked to maternal autoimmunity against cardiac myosin.

Structural congenital heart disease (CHD) has not previously been linked to autoimmunity. In our study, we developed an autoimmune model of structural CHD that resembles hypoplastic left heart syndrome (HLHS), a life-threatening CHD primarily affecting the left ventricle. Because cardiac myosin (CM) is a dominant autoantigen in autoimmune heart disease, we hypothesized that immunization with CM might lead to transplacental passage of maternal autoantibodies and a prenatal HLHS phenotype in exposed fetuses. Elevated anti-CM autoantibodies in maternal and fetal sera, as well as IgG reactivity in fetal myocardium, were correlated with structural CHD that included diminished left ventricular cavity dimensions in the affected progeny. Further, fetuses that developed a marked HLHS phenotype had elevated serum titers of anti-ß-adrenergic receptor Abs, as well as increased protein kinase A activity, suggesting a potential mechanism for the observed pathological changes. Our maternal-fetal model presents a new concept linking autoimmunity against CM and cardiomyocyte proliferation with cardinal features of HLHS. To our knowledge, this report shows the first evidence in support of a novel immune-mediated mechanism for pathogenesis of structural CHD that may have implications in its future diagnosis and treatment.

Role for immune monitoring to tailor induction prophylaxis in pediatric heart recipients.

UNLABELLED: rATG is used for HTx induction but is costly and associated with infection and PTLD. HYPOTHESIS: Tailoring rATG induction with CD3 monitoring results in less infection, reduced costs, and similar rejection. Retrospective review of HTx recipients receiving rATG induction. Control cases received "usual" rATG dosing (1.5 mg/kg/day typically × 5 days). Starting in October 2009, absolute CD3 monitoring (target <25 cells/mm(3) ) guided rATG dosing (study cases). Outcomes included first-year incidence of infection/rejection, direct costs of therapy, and incidence of PTLD/death. Study cases (n = 32) received fewer doses of rATG (median 4 vs. 5, p < 0.001) and less total rATG (median 3.2 vs. 7.4 mg/kg, p < 0.001) compared with controls (n = 17). There was no difference in incidence of infection, rejection, or patient survival during the first year post-HTx. There was one early death in both groups and one late case of PTLD in the control group. Drug savings were significant (median drug cost per patient $2718 vs. $4756, p < 0.001). CD3-tailored rATG induction in HTx recipients is associated with reduced drug costs and similar rates of rejection/infection. Longer follow-up will determine whether extended benefits are associated with this induction monitoring strategy.

Cardiac troponin I, cardiac troponin-specific autoantibodies and natriuretic peptides in children with hypoplastic left heart syndrome.

OBJECTIVES: To evaluate serum levels of cardiac troponin I (cTnI), autoantibodies against cardiac troponin (cTnAAbs) and natriuretic peptides during the treatment protocol in children with hypoplastic left heart syndrome (HLHS). METHODS: In a prospective study, we had 18 consecutive children with HLHS, for whom serum samples were analysed before the Norwood operation, before the bidirectional Glenn (BDG) operation, at the age of one year and before total cavo-pulmonary connection (TCPC). In addition, we performed a cross-sectional study in 22 children examined before TCPC. Controls comprised 34 healthy children. RESULTS: In the prospective study, troponin I was positive in eight children before the Norwood operation. At the next follow-up, six children were positive. Thereafter, in all samples, cTnI was negative. Serum levels of natriuretic peptides decreased during the treatment protocol but remained higher than in controls throughout the study. In the cross-sectional study, cTnI levels were negative, but levels of natriuretic peptides were higher than in controls. Levels of cTnI and natriuretic peptides showed no correlation with oxygen saturation or haemoglobin concentration. Autoantibodies against cardiac troponin appeared in one patient but not in the control children. CONCLUSIONS: Cardiac TnI release is common before Norwood and BDG operations; then during the treatment protocol for HLHS, cTnI release resolves and serum levels of natriuretic peptides decrease. This may reflect a reduction of volume overload of the right ventricle during the surgical programme.

Failure of prophylactic intravenous immunoglobulin to prevent sensitization to cryopreserved allograft tissue used in congenital cardiac surgery.

OBJECTIVE: Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome causes profound immunologic sensitization, which may complicate future transplantation. Intravenous immunoglobulin has been shown to reduce sensitization after it has developed, allowing successful transplantation. The purpose of this pilot trial was to determine whether intravenous immunoglobulin given before and after the procedure could prevent sensitization to cryopreserved allograft patches used in the initial repair of hypoplastic left heart syndrome. METHODS: Intravenous immunoglobulin (2 g/kg) was given preoperatively, 3 weeks postoperatively, and 4 months postoperatively to 7 infants undergoing the Norwood procedure. Panel-reactive antibodies were measured with flow cytometry preoperatively and at 1, 4, 6, and 12 months postoperatively and compared with values from a contemporary cohort of 12 infants undergoing the Norwood procedure who did not receive intravenous immunoglobulin. RESULTS: The groups were well matched for length and weight at time of surgery. Control infants were somewhat younger than the cohort receiving intravenous immunoglobulin (8 +/- 5 vs 17 +/- 14 days, P = .021). There were no differences in transfusion requirements. There was no difference in the degree of sensitization between control and intravenous immunoglobulin groups at 1 month (class I panel-reactive antibodies 20% +/- 30% vs 4% +/- 9%, P = .443, class II panel-reactive antibodies 17% +/- 27% vs 20% +/- 17%, P = .400), 4 months (class I panel-reactive antibodies 62% +/- 40% vs 73% +/- 41%, P = .813, class II panel-reactive antibodies 49% +/- 42% vs 54% +/- 41%, P = .706), and 12 months (class I panel-reactive antibodies 49% +/- 42% vs 58% +/- 39%, P = .686, class II panel-reactive antibodies 44% +/- 36% vs 49% +/- 42%, P = .651). CONCLUSION: Despite studies showing intravenous immunoglobulin to reduce sensitization, we were unable to demonstrate that intravenous immunoglobulin prevented sensitization after exposure to allograft tissue in neonates undergoing congenital cardiac surgery.

Pediatric heart transplantation across ABO blood type barriers: a case study.

Heart transplantation with ABO blood type-incompatible donors has historically been contraindicated because of the high risk of an immediate hyperacute humoral graft rejection. The immature neonatal immune system presents an immunologic window that allows for breaching the ABO barrier before the natural development of anti-ABO antibodies. Information from a small series of neonates has demonstrated similar survival rates and posttransplant outcomes compared to ABO-compatible transplantations. In the posttransplant period, particular attention is placed on the surveillance of graft-specific antibody production and monitoring for immunologic signs and symptoms of early graft vasculopathy. This article presents a case study of a neonate with congenital heart disease who underwent one of the first successful ABO-incompatible heart transplantations in the United States.

Use of an allograft patch in repair of hypoplastic left heart syndrome may complicate future transplantation.

OBJECTIVE: Cryopreserved allograft tissue used in the Norwood procedure for infants with hypoplastic left heart syndrome (HLHS) has the potential to cause marked immunologic sensitization which may complicate potential future heart transplantation, if required. The purpose of this study was to assess the anti-HLA antibody response to allograft patches used in the initial repair of HLHS. METHODS: A prospective cohort study was conducted comparing the panel-reactive antibody levels (PRA) in 12 infants undergoing repair of HLHS with cryopreserved allograft patch to 10 infants undergoing arterial switch for transposition of the great arteries (no allograft tissue used). PRA for Class I (HLA-A, B, C) and Class II (HLA-DR, DQ) antibodies were assessed preoperatively and postoperatively using flow cytometry. RESULTS: The two groups were well matched at the time of surgery (age, weight, gender). Infants in both groups received blood from multiple donors; however, the allograft group received significantly more (12+/-10 vs. 5+/-1 units; P<0.001). By 4 months, most infants receiving allograft tissue had become highly sensitized for both Class I PRA (62+/-40 vs. 0; P=0.002) and Class II PRA (49+/-42 vs. 2+/-3; P=0.022). This response continued to increase at 12 months: Class I PRA (79+/-21 vs. 0; P=0.008) and Class II PRA (66+/-27 vs. 5+/-6; P=0.008). Specificity analysis confirmed antibodies were specific for the donor allograft HLA type. In addition, infants who were coincidently HLA-matched with their allograft did not develop an elevated PRA. CONCLUSIONS: Allograft tissue used in the repair of HLHS is associated with profound donor specific immunologic sensitization in the majority of recipients and may complicate or jeopardize future transplantation. Methods to reduce the immunogenicity of cryopreserved allograft tissue used for arch reconstruction requires further investigation.