Clinical presentation, genetic etiology and outcome associated with fetal cardiomyopathy: comparison of two eras

OBJECTIVE

To assess the rate and type of genetic diagnosis and clinical outcome of cases of fetal cardiomyopathy (CM) during two eras, in order to examine the impact of advanced genetic testing and improved perinatal management strategies.

METHODS

All diagnoses of fetal CM in Alberta, Canada, encountered between 2003 and 2019, were reviewed retrospectively. Genetic, cardiac and non-cardiac diagnoses and clinical outcome were documented. Cases with CM secondary to extracardiac pathology and maternal conditions were excluded. Cases diagnosed in the earlier era of the study period (2003-2012) were compared with those diagnosed in the later era (2013-2019).

RESULTS

Thirty-eight cases of fetal CM met the inclusion criteria. Median gestational age (GA) at diagnosis was 22.8 (range, 13.4-37.4) weeks. Associated structural heart disease was present in 39% (15/38) of cases and 24% (9/38) had arrhythmia. Hydrops was identified in 29% (11/38) of cases at presentation, and a further 18% (7/38) developed hydrops later in gestation. Twenty-six percent (10/38) of cases underwent termination of pregnancy and 24% (9/38) had intrauterine death. Of liveborn cases, neonatal death occurred in 16% (3/19), late death occurred in 21% (4/19) and 63% (12/19) were alive at the last follow-up. Excluding cases that had termination of pregnancy and those with a liveborn infant who received planned palliative care, the rate of neonatal survival was higher in the later compared with the earlier era (69% (11/16) vs 45% (5/11)), although the difference was not statistically significant (P = 0.26). A genetic etiology was confirmed in 39% (15/38) of cases and strongly suspected in 24% (9/38). A significantly higher proportion of cases had a confirmed or strongly suspected genetic etiology in the later era compared with in the earlier era (76% (19/25) vs 38% (5/13); P = 0.04).

CONCLUSIONS

In the recent era, a higher proportion of fetal CM cases had a confirmed or strongly suspected genetic etiology than reported previously. Based on comparison with older series, modern perinatal management strategies may not have a significant impact on neonatal survival in cases of fetal CM; however, a larger study would be better powered to detect more subtle differences. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry

BACKGROUND

Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes.

METHODS

The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers.

RESULTS

A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival.

CONCLUSIONS

Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

Distinct remodeling pattern between pediatric and adult heart failure: a focus on Ca2+ signaling pathway at proteomic level

Background

Dilated cardiomyopathy (DCM) is among the most common causes leading to end-stage heart failure with reduced ejection fraction (HF-rEF) in adult and pediatric patients. Despite similar phenotypes characterized as systolic dysfunction and eccentric ventricular dilation, pediatric DCM are biologically distinct entities with age- and development-specific features in the heart. Though underlying mechanisms may vary between the two populations, it's largely unexplored with few studies conducted to date.

Purpose

HF-rEF typically results from impaired myocardial contractility, triggered by defective cellular Ca2+ handling and cytoskeletal remodeling. Hence, we aim to integrate clinical profile and experimental data from human explanted hearts: 1) to unravel the age-dependent disparate Ca2+ signaling pathways; and 2) to identify pediatric-specific HF signatures or potential cures for precision managements.

Methods

Non-ischemic failing hearts (n=6 adult and n=6 pediatric) were procured immediately after excision via Human Explanted Heart Program. Age-matched adult non-failing control hearts (NFC, n=6) were obtained from deceased donors without cardiovascular history, while pediatric NFC (n=6) were collected from children with congenital heart defects but no primary myocardial dysfunction constituting relatively reasonable controls. Myocardial metabolic and oxidative profile were evaluated spectrophotometrically, and tissue remodeling was assessed immunohistochemically. Global proteomics and phosphoproteomics were performed on a Q-Exactive mass spectrometer, followed by network biology pathway analyses. Expression of screened proteins and kinases was validated by gel electrophoresis. Apoptosis and cellular growth signaling pathways were also incorporated into analysis.

Results

Both HF groups had remarkably lower LVEF (26.6±10.7% in pediatric vs. 26.5±9.1% in adult DCM) while compared to the NFC (both ≥60%) respectively. Histologically, adult-DCM demonstrated significantly worse fibrosis than pediatric-DCM (p<0.01). It was consistent with excessive reactive oxygen species (ROS) production and perturbed anti-ROS defense noted in adult-DCM, indicative of possible reverse remodeling in the pediatric failing hearts with shorter course of illness till transplant. Mechanistically, NCX1 was elevated with SERCA2 decreased in adult-DCM versus adult-NFC (p<0.05), while both pediatric groups exhibited comparable levels. Reduced p-/t-phospholamban and p-/t-CaMK in adult-DCM, unlike in pediatric-DCM, also illustrated altered phosphorylation patterns. Moreover, GSK-3β and AMPK pathways were inhibited while AKT-473 was activated in adult-DCM.

Conclusions

Pediatric DCM exhibited less adverse remodeling partially mediated by divergent Ca2+ handling and downstream signaling pathways, illustrating the fundamental differences between adult and pediatric DCM. Our findings may provide a scientific basis for the development of specific therapies for pediatric DCM.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Canadian Institutes for Health Research (CIHR); Heart & Stroke Foundation (HSF)

Randomized controlled trial of high-dose intradermal versus standard-dose intramuscular influenza vaccine in organ transplant recipients

The immunogenicity of standard intramuscular (IM) influenza vaccine is suboptimal in transplant recipients. Also, recent studies suggest that alloantibody may be upregulated due to vaccination. We evaluated a novel high-dose intradermal (ID) vaccine strategy. In conjunction, we assessed alloimmunity. Transplant recipients were randomized to receive IM or high-dose ID vaccine. Strain-specific serology and HLA alloantibody production was determined pre- and postimmunization. In 212 evaluable patients (105 IM, 107 ID), seroprotection to H1N1, H3N2 and B strains was 70.5%, 63.8% and 52.4% in the IM group, and 71.0%, 70.1%, 63.6% in the ID group (p=ns). Seroconversion to ≥1 antigen was 46.7% and 51.4% in the IM and ID groups respectively (p=0.49). Response was more likely in those≥6 months posttransplant (53.2% vs. 19.2%; p=0.001). Use of mycophenolate mofetil was inversely associated with vaccine response in a dose-dependent manner (p<0.001). Certain organ subgroups had higher response rates for influenza B in the ID vaccine group. Differences in anti-HLA antibody production were detected in only 3/212(1.4%) patients with no clinical consequences. High-dose intradermal vaccine is an alternative to standard vaccine and has potential enhanced immunogenicity in certain subgroups. In this large cohort, we also show that seasonal influenza does not result in significant alloantibody production.

Successful ABO-incompatible heart transplantation in a child despite blood-group sensitization after ventricular assist device support

In the first two yr of life blood-group incompatible (ABO-incompatible) heart transplantation can be performed leading to immune tolerance to donor blood group. Antibody titers should be below 1:4. VAD use is correlated with sensitization toward blood-group antigens. A boy was diagnosed with dilated cardiomyopathy at nine months of age and listed for 0-compatible transplantation. Progressive heart failure required implantation of a left VAD. His listing was extended for ABO-incompatible transplantation despite antibody titers of 1:32 anti-A and 1:8 anti-B. After 26 days on VAD, he was transplanted with a B donor heart. No hyperacute or acute rejection occurred in 12 months post-transplant. Anti-B antibodies rose to a maximum of 1:2. No use of rituximab or plasmapheresis was required. There are no signs of graft vasculopathy. This indicates that inclusion criteria for ABO-incompatible transplantation may be extended to immediate cases. This is the first case with a healthy immune system to show signs of tolerance development after ABO-incompatible heart transplantation with increased prior antibody titers and without specific treatment.

Recurrent pericarditis in children: elevated cardiac autoantibodies

Recurrent pericarditis is a rare disease in childhood. Nevertheless, it may represent a challenge to the clinician due to its resistance to anti-inflammatory treatment. The initial etiology often remains unclear; specific laboratory parameters predicting the frequency or severity of the recurrences are lacking. We report on four patients with recurrent pericarditis in whom antimyolemmal antibodies (AMLAs) were detected. A prolonged persistence of IgM-type AMLAs was found in three patients: two of them presented with acute inflammation as the initial event and one with 48 recurrences during 5.5 years. The fourth patient showed a fast conversion from IgM to IgG-type AMLAs after a less acute initial presentation and showed 4 mild recurrences during the 48-month follow-up.

CONCLUSION

We were able to detect AMLAs in four children with recurrent pericarditis. This finding may be attributed to an auto-immunological disease following a first, acute event. We propose the detection of AMLAs in all children with unexplained recurrent pericarditis. Pediatric patients with a persistence of IgM-type AMLAs may face frequent recurrences and should be monitored therefore more closely. In addition, medical treatment may be changed in these patients with a slower tapering of the dosage of steroidal and non-steroidal antiinflammatory drugs.

Spatiotemporal transcription of connexin45 during brain development results in neuronal expression in adult mice

Characterization of the expression pattern of connexins in neural tissue is a necessary prerequisite for understanding the functional relevance of the corresponding gap junction channels in brain. Here we describe the cell type-specific expression of connexin45 in the CNS and the spatiotemporal expression pattern from embryonic day 19.5 to adult brain using a recently described connexin45 LacZ-reporter mouse. The connexin45 gene is highly expressed during embryogenesis and up to 2 weeks after birth in nearly all brain regions. Afterward its expression is restricted to the thalamus, the CA3 region of hippocampus and the cerebellum. In adult mouse brain, the pattern of LacZ-staining in combination with the analysis of different neuronal and glial marker proteins strongly suggests that connexin45 is expressed in neurons, but presumably not in astrocytes or mature oligodendrocytes. Expression of the LacZ/connexin45 reporter gene in subsets of neurons, such as cerebral cortical, hippocampal and thalamic neurons as well as basket and stellate cells of cerebellum should be corroborated by functional investigations of connexin45 protein in electrical synapses. Based on its expression pattern during development, we suggest that the connexin45-containing gap junction channels have a rather ubiquitous role during brain development and may contribute to functional specification in certain subsets of neurons in the adult brain.

Expression pattern of galectin-3 in neural tumor cell lines

Galectin-3 is a member of the galectin family of beta-galactoside-specific animal lectins. Here we show that galectin-3 is constitutively expressed in 15 out of 16 glioma cell lines tested, but not by normal or reactive astrocytes, oligodendrocytes, glial O-2A progenitor cells and the oligodendrocyte precursor cell line Oli-neu. Galectin-3 is also expressed by one oligodendroglioma cell line, but not by primitive neuroectodermal tumor and 4 neuroblastoma cell lines tested so far. In all galectin-3 expressing cell lines, the lectin is predominantly, if not exclusively, localized intracellularly and carries an active carbohydrate recognition domain (shown for C6 rat glioma cells). Moreover, in contrast to primary astrocytes, glioma cells do not or only weakly adhere to substratum-bound galectin-3, probably reflecting an unusual glycosylation pattern. Our findings indicate that the expression of galectin-3 selectively correlates with glial cell transformation in the central nervous system and could thus serve as a marker for glial tumor cell lines and glial tumors.

Murine microglial cells express functionally active galectin-3 in vitro

In the present study we have analyzed the expression of galectin-3, a beta-galactoside-specific soluble animal lectin, by microglial cells in vitro. In enriched microglial cell cultures derived from neonatal mouse brain after 2 to 3 weeks in vitro, almost all microglial cells expressed galectin-3 intracellularly and about 90% expressed the molecule on the cell surface. Western blot analyses of lysates from microglial cells using galectin-3-specific antibodies revealed a single band with an apparent molecular weight of 29 kD. The carbohydrate recognition domain of microglia-derived galectin-3 was functional as the molecule could be affinity purified on lactose-agarose. Upon an incubation with lactose-, but not with sucrose-containing buffers the amount of cell surface expressed galectin-3 was strongly reduced, suggesting that the molecule appears to be associated with the plasma membrane via its carbohydrate recognition domain. The total amount as well as the portion of cell surface expressed galectin-3 increased upon treatment with granulocyte-macrophage colony-stimulating factor. Our findings suggest that galectin-3 expression is subject to regulation by growth factors supposed to be involved in the cascade of microglial activation under pathological conditions.