Spontaneous evolution patterns of focal congenital hepatic hemangiomas: a case series of 25 patients.

BACKGROUND: Hepatic hemangiomas are the most common benign liver tumors of infancy. They are termed congenital if fully developed at birth or infantile if they appear in the first weeks of life. Previous studies suggested that most focal hepatic hemangiomas are congenital in nature, exhibit no postnatal growth and have an evolution that parallels their cutaneous counterparts. They are subdivided by pattern of involution, whether rapidly involuting (RICH), partially involuting (PICH) or non-involuting (NICH) congenital hemangiomas. In our experience, some focal hepatic hemangiomas show postnatal growth, behaving like infantile forms. OBJECTIVES: To analyze the spontaneous evolution of focal congenital hepatic hemangiomas with quantification of tumor volume changes over time and to identify initial postnatal ultrasound (US) imaging biomarkers predictive of their evolution pattern. MATERIALS AND METHODS: A retrospective review of clinical, imaging and pathology data of children diagnosed with focal congenital hepatic hemangioma (prenatal diagnosis or age at diagnosis <7 days and/or glucose transporter protein 1 [GLUT1]-negative tumor) diagnosed between 2000 and 2018 was performed with analysis of tumor volume changes over time. Exclusion criteria were treatment inducing a tumor volume change (hepatic artery embolization, propranolol, or corticosteroids), imaging follow-up less than 1 month or fewer than two US examinations. Volumetric analysis was based on US and cross-sectional imaging. Lesion volumes were estimated using the standard ellipsoid formula. A 35% margin of error was assumed for tumor volume variation to account for variability in measurements. Imaging studies, including US, computed tomography, and magnetic resonance imaging, were reviewed and initial postnatal US features were correlated with evolution pattern. RESULTS: Twenty-five patients with focal congenital hepatic hemangiomas were included. The median follow-up time was 46.5 months (range: 4-144 months). Eight (32%) lesions showed postnatal growth before involuting, without signs of intralesional hemorrhage, as do cutaneous infantile hemangiomas. The other 17 (68%) lesions exhibited a strict decrease in volume with age, of which 15 underwent complete involution (8 before age 18 months and 7 after age 18 months) and 2 underwent partial involution. The different evolution patterns of focal congenital hepatic hemangiomas showed overlapping imaging features and we found no initial US feature to be significantly associated with postnatal growth. However, large vascular spaces with marked vascularity at US were noted in three of the eight rapidly involuting lesions. CONCLUSION: Focal congenital hepatic hemangiomas are not the equivalent of cutaneous RICH, as some may increase in size and tumor regression may be rapid or slow. The different evolution patterns of focal congenital hepatic hemangiomas show overlapping US features.

Cardiovascular disorders in patients with congenital portosystemic shunts: 23 years of experience in a tertiary referral centre.

BACKGROUND: Congenital portosystemic shunts are rare vascular malformations that may have an impact on the heart-lung system. Associated congenital and/or acquired heart diseases are poorly reported. AIMS: To analyse cardiovascular disorders within a large congenital portosystemic shunt population, and develop a diagnostic strategy. METHODS: Among the 168 consecutive fetuses and children referred for congenital portosystemic shunt (1996-2019), patients presenting with at least one cardiovascular disorder, including congenital heart disease, heart failure, portopulmonary hypertension and/or hepatopulmonary syndrome, were reviewed retrospectively. Cardiovascular disorders were detected using echocardiography and one or more of the following: right-sided heart catheterization; contrast-enhanced transthoracic echocardiography; or lung perfusion radionuclide scan. RESULTS: Overall, 46/168 patients with a congenital portosystemic shunt (27.4%) had one or more clinically significant cardiovascular disorders. Congenital heart disease was present in 28 patients, including six with left heterotaxy. Heart failure was present in six fetuses and 21 neonates (eight without congenital heart disease, and 13 with congenital heart disease). In neonates without congenital heart disease, heart function recovered by the age of 3years. Portopulmonary hypertension was identified in 11 patients (mean age at diagnosis: 9years); it was fatal in one patient, and remained stable in five of six patients after congenital portosystemic shunt closure. In six patients, hepatopulmonary syndrome presented as hypoxia (mean age at diagnosis: 5.3years), which reversed after congenital portosystemic shunt closure. CONCLUSIONS: Evaluation and monitoring of the cardiopulmonary status of patients with a congenital portosystemic shunt is mandatory to detect and prevent cardiovascular complications. Furthermore, congenital portosystemic shunts must be sought in patients with unexplained cardiovascular disorders, especially when malformations are present.

SponGee: A Genetic Tool for Subcellular and Cell-Specific cGMP Manipulation.

cGMP is critical to a variety of cellular processes, but the available tools to interfere with endogenous cGMP lack cellular and subcellular specificity. We introduce SponGee, a genetically encoded chelator of this cyclic nucleotide that enables in vitro and in vivo manipulations in single cells and in biochemically defined subcellular compartments. SponGee buffers physiological changes in cGMP concentration in various model systems while not affecting cAMP signals. We provide proof-of-concept strategies by using this tool to highlight the role of cGMP signaling in vivo and in discrete subcellular domains. SponGee enables the investigation of local cGMP signals in vivo and paves the way for therapeutic strategies that prevent downstream signaling activation.

Polarized cellular patterns of endocannabinoid production and detection shape cannabinoid signaling in neurons.

Neurons display important differences in plasma membrane composition between somatodendritic and axonal compartments, potentially leading to currently unexplored consequences in G-protein-coupled-receptor signaling. Here, by using highly-resolved biosensor imaging to measure local changes in basal levels of key signaling components, we explored features of type-1 cannabinoid receptor (CB1R) signaling in individual axons and dendrites of cultured rat hippocampal neurons. Activation of endogenous CB1Rs led to rapid, Gi/o-protein- and cAMP-mediated decrease of cyclic-AMP-dependent protein kinase (PKA) activity in the somatodendritic compartment. In axons, PKA inhibition was significantly stronger, in line with axonally-polarized distribution of CB1Rs. Conversely, inverse agonist AM281 produced marked rapid increase of basal PKA activation in somata and dendrites, but not in axons, removing constitutive activation of CB1Rs generated by local production of the endocannabinoid 2-arachidonoylglycerol (2-AG). Interestingly, somatodendritic 2-AG levels differently modified signaling responses to CB1R activation by Δ(9)-THC, the psychoactive compound of marijuana, and by the synthetic cannabinoids WIN55,212-2 and CP55,940. These highly contrasted differences in sub-neuronal signaling responses warrant caution in extrapolating pharmacological profiles, which are typically obtained in non-polarized cells, to predict in vivo responses of axonal (i.e., presynaptic) GPCRs. Therefore, our results suggest that enhanced comprehension of GPCR signaling constraints imposed by neuronal cell biology may improve the understanding of neuropharmacological action.

Activation-dependent plasticity of polarized GPCR distribution on the neuronal surface.

Directionality of information flow through neuronal networks is sustained at cellular level by polarized neurons. However, specific targeting or anchoring motifs responsible for polarized distribution on the neuronal surface have only been identified for a few neuronal G-protein-coupled receptors (GPCRs). Here, through mutational and pharmacological modifications of the conformational state of two model GPCRs, the axonal CB1R cannabinoid and the somatodendritic SSTR2 somatostatin receptors, we show important conformation-dependent variations in polarized distribution. The underlying mechanisms include lower efficiency of conformation-dependent GPCR endocytosis in axons, compared with dendrites, particularly at moderate activation levels, as well as endocytosis-dependent transcytotic delivery of GPCRs from the somatodendritic domain to distal axonal portions, shown by using compartmentalized microfluidic devices. Kinetic modeling predicted that GPCR distribution polarity is highly regulated by steady-state endocytosis, which is conformation dependent and is able to regulate the relative amount of GPCRs targeted to axons and that axonally polarized distribution is an intermediary phenotype that appears at moderate basal activation levels. Indeed, we experimentally show that gradual changes in basal activation-dependent endocytosis lead to highly correlated shifts of polarized GPCR distribution on the neuronal surface, which can even result in a fully reversed polarized distribution of naturally somatodendritic or axonal GPCRs. In conclusion, polarized distribution of neuronal GPCRs may have a pharmacologically controllable component, which, in the absence of dominant targeting motifs, could even represent the principal regulator of sub-neuronal distribution. Consequently, chronic modifications of basal GPCR activation by therapeutic or abused drugs may lead to previously unanticipated changes in brain function through perturbation of polarized GPCR distribution on the neuronal surface.

Type-1 cannabinoid receptor signaling in neuronal development.

The type-1 cannabinoid receptor (CB1R) was initially identified as the neuronal target of Δ(9)-tetrahydrocannabinol (THC), the major psychoactive substance of marijuana. This receptor is one of the most abundant G-protein-coupled receptors in the adult brain, the target of endocannabinoid ligands and a well-characterized retrograde synaptic regulator. However, CB1Rs are also highly and often transiently expressed in neuronal populations in the embryonic and early postnatal brain, even before the formation of synapses. This suggests important physiological roles for CB1Rs during neuronal development. Several recent reviews have summarized our knowledge about the role of the endocannabinoid (eCB) system in neurodevelopment and neurotransmission by focusing on the metabolism of endocannabinoid molecules. Here, we review current knowledge about the effects of the modulation of CB1R signaling during the different phases of brain development. More precisely, we focus on reports that directly implicate CB1Rs during progenitor cell migration and differentiation, neurite outgrowth, axonal pathfinding and synaptogenesis. Based on theoretical considerations and on the reviewed experimental data, we propose a new model to explain the diversity of experimental findings on eCB signaling on neurite growth and axonal pathfinding. In our model, cell-autonomus and paracrine eCBs acting on CB1Rs are part of a global inhibitory network of cytoskeletal effectors, which act in concert with positive-feedback local-excitation loops, to ultimately yield highly polarized neurons.