Revisión Sistemática Exploratoria sobre Uso de Óxido Nítrico Inhalado para Evaluación de Reactividad Vascular Pulmonar en Laboratorio de Hemodinamia en Sujetos Pediátricos con Hipertensión Pulmonar / Exploratory Systematic Review on the Use of Inhaled Nitric Oxide for Evaluation of Pulmonary Vascular Reactivity in Hemodynamics Laboratory in Pediatric Subjects with Pulmonary Hypertension

Introducción. La hipertensión arterial pulmonar (HAP) es una enfermedad que presenta un elevado índice de mortalidad en la población pediátrica. Para su diagnóstico, el gold standard es la prueba de reactividad vascular pulmonar (PRVP), debido a que permite medir la respuesta vasodilatadora del lecho vascular pulmonar frente a la administración de moléculas con acción terapéutica, como el óxido nítrico inhalado (iNO). Esta prueba al ser positiva se asocia a un mejor pronóstico. En la actualidad existe incertidumbre y falta de consenso sobre la indicación y administración de iNO durante la PRVP. Objetivo. Describir el uso reportado en la literatura sobre iNO en PRVP en sujetos pediátricos con HAP. Métodos. Revisión sistemática exploratoria sensible en bases de datos PubMed, Epistemonikos, Cochrane, Scopus, Lilacs y Scielo, que describen el uso de iNO durante la PRVP en sujetos pediátricos con HAP. Resultados. se identificaron 8.906 artículos, de los cuales se seleccionaron 5 para la revisión cualitativa. La PRVP se realizó durante el cateterismo cardiaco derecho (CCD) en sujetosentre 2 semanas y 18 años de edad. Los diagnósticos fueron HAP primaria, idiopática y asociada a patología cardiaca congénita, cardiomiopatía y enfermedad pulmonar. Esta prueba fue realizada en sujetos sólo con soporte de oxígeno o con sedación profunda en ventilación mecánica invasiva, con dosis variables de oxígeno (21 y 100%) e iNO (3 y 80 ppm), o asociado a otras moléculas como iloprostol®, dilitiazem, sildenafil y/o epoprostenol. La administración de iNO disminuyó presión de arteria pulmonar y la resistencia vascular pulmonar, con mantención de presión arterial sistémica y gasto cardiaco y sin complicaciones asociadas a su uso. Conclusiones. Existen escasos estudios sobre iNO en PRVP pediátrica y con calidad metodológica limitada. El iNO se utiliza como método diagnóstico de vaso reactividad en sujetos pediátricos con HAP asociada a cardiopatía congénita, primaria o secundaria. Los protocolos para su uso son variables con dosis entre 20 y 40 ppm, con o sin uso de oxigeno adicional, con tiempos poco precisos y sin consenso en equipos de administración.

Background. Pulmonary arterial hypertension (PAH) is a disease that has a high mortality rate among the pediatric population. For its diagnosis, the pulmonary vascular reactivity test (PVRT) is considered the "Gold Standard", because it allows to measure the vasodilator response of pulmonary vascular circulation with the administration of molecules with therapeutic action, such as inhaled nitric oxide (iNO). This test, when positive, is associated with a better prognosis of the disease. Currently, there's uncertainty and lack of consensus on the indication and administration of iNO during the PVRT. Objetives. to describe use of iNO in PVRT in pediatric users with PAH reported in the literature. Methods. Scoping review of studies published between 1992 and 2021 in PubMed, Epistemonikos, Cochrane, Scopus, Lilacs and Scielo databases, which describe the use of iNO during PVRT in pediatric users with PAH, in English and Spanish. Primary and secondary studies with a sensitive search strategy were considered. Results. 8,906 articles were identified, 40 were selected by title, 8 by full text, and 5 for final qualitative review. Of the total of articles selected, 3 were primary and 2 secondary studies. PVRT was performed during right heart catheterization (RHC) in a population between 2 weeks and 18 years old. Diagnoses were primary PAH, idiopathic PAH and PAH associated with congenital heart disease, cardiomyopathy and pulmonary disease. This test was carried out in subjects on spontaneous ventilation with oxygen support or with deep sedation in invasive mechanical ventilation, with variable oxygen doses between 21 and 100%, with exclusive use of iNO between 3 and 80 ppm, being more used between 20 and 40 ppm, or associated with other molecules such as iloprostol®, dilithiazim, sildenafil and / or epoprostenol. In all selected studies, administration of iNO decreased PAP (pulmonary artery pressure) and PVR (pulmonary vascular resistance), with maintenance of SBP (systemic arterial blood pressure) and cardiac output. The primary studies were made up of pre and post-test of serial or parallel interventions. The selected studies of iNO in PVRT did not report complications associated with its use. Conclusions. studies on iNO in pediatric PVRT are scarce in number of publications and methodological quality. iNO is used as a diagnostic method of vasoreactivity in pediatric users with PAH associated with congenital, primary, or secondary heart disease. The protocols for its use are variable with recommended doses between 20 and 40 ppm, with or without the use of additional O2, with imprecise times and without consensus in administration equipment. The response to PVRT serves as a guide for the treatment and prognosis of pediatric users with PAH.

c-Abl Activation Linked to Autophagy-Lysosomal Dysfunction Contributes to Neurological Impairment in Niemann-Pick Type A Disease.

Niemann-Pick type A (NPA) disease is a fatal lysosomal neurodegenerative disorder caused by the deficiency in acid sphingomyelinase (ASM) activity. NPA patients present severe and progressive neurodegeneration starting at an early age. Currently, there is no effective treatment for this disease and NPA patients die between 2 and 3 years of age. NPA is characterized by an accumulation of sphingomyelin in lysosomes and dysfunction in the autophagy-lysosomal pathway. Recent studies show that c-Abl tyrosine kinase activity downregulates autophagy and the lysosomal pathway. Interestingly, this kinase is also activated in other lysosomal neurodegenerative disorders. Here, we describe that c-Abl activation contributes to the mechanisms of neuronal damage and death in NPA disease. Our data demonstrate that: 1) c-Abl is activated in-vitro as well as in-vivo NPA models; 2) imatinib, a clinical c-Abl inhibitor, reduces autophagy-lysosomal pathway alterations, restores autophagy flux, and lowers sphingomyelin accumulation in NPA patient fibroblasts and NPA neuronal models and 3) chronic treatment with nilotinib and neurotinib, two c-Abl inhibitors with differences in blood-brain barrier penetrance and target binding mode, show further benefits. While nilotinib treatment reduces neuronal death in the cerebellum and improves locomotor functions, neurotinib decreases glial activation, neuronal disorganization, and loss in hippocampus and cortex, as well as the cognitive decline of NPA mice. Our results support the participation of c-Abl signaling in NPA neurodegeneration and autophagy-lysosomal alterations, supporting the potential use of c-Abl inhibitors for the clinical treatment of NPA patients.

Sarcopenia Induced by Chronic Liver Disease in Mice Requires the Expression of the Bile Acids Membrane Receptor TGR5.

Sarcopenia is a condition of muscle dysfunction, commonly associated with chronic liver disease (CLD), characterized by a decline in muscle strength, the activation of the ubiquitin-proteasome system (UPS), and oxidative stress. We recently described a murine model of CLD-induced sarcopenia by intake of hepatotoxin 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), which presents an increase in plasma bile acids (BA). BA induced skeletal muscle atrophy through a mechanism dependent on the Takeda G protein-coupled receptor 5 (TGR5) receptor. In the present study, we evaluated the role of TGR5 signaling in the development of sarcopenia using a model of DDC-induced CLD in C57BL6 wild-type (WT) mice and mice deficient in TGR5 expression (TGR5-/- mice). The results indicate that the decline in muscle function and contractibility induced by the DDC diet is dependent on TGR5 expression. TGR5 dependence was also observed for the decrease in fiber diameter and sarcomeric proteins, as well as for the fast-to-slow shift in muscle fiber type. UPS overactivation, indicated by increased atrogin-1/MAFbx (atrogin-1) and muscle RING-finger protein-1 (MuRF-1) protein levels and oxidative stress, was abolished in tibialis anterior muscles from TGR5-/- mice. Our results collectively suggest that all sarcopenia features induced by the DDC-supplemented diet in mice are dependent on TGR5 receptor expression.

Sarcopenia in a mice model of chronic liver disease: role of the ubiquitin-proteasome system and oxidative stress.

Sarcopenia is the loss of muscle mass and strength produced by aging or secondary to chronic diseases such as chronic liver disease (CLD). Although not all types of sarcopenia involve the same features, the most common are decreased fiber diameter and myosin heavy chain (MHC) levels, increased activity of ubiquitin-proteasome system (UPS) and reactive oxygen species (ROS). In this study, we aim to characterize the development of sarcopenia secondary to CLD induced by the hepatotoxin 5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). For this purpose, four-months-old male C57BL6 mice were fed with normal diet or DDC supplemented diet for 6 weeks. Functional tests to evaluate muscle strength, mobility, and motor skills were performed in alive mice. The muscle strength in isolated gastrocnemius was also assayed via electrophysiological measurements. Morphometric measures of fibers' diameter, total and ubiquitinated protein levels of myosin heavy chain (MHC), E3 ubiquitin ligases, ROS, and oxidation-dependent modified proteins in gastrocnemius tissue were also determined. Our results demonstrated that mice fed the DDC diet developed muscle wasting as evidenced by a loss of muscle mass and decreased muscle strength. The muscles of mice fed with DDC diet have a decreased diameter of fibers and MHC levels, also as increased MuRF-1 and atrogin-1 protein levels, ROS levels, and oxidation-modified protein levels. Additionally, control and DDC mice have the same food and water intake as well as mobility. Our results demonstrate mice with CLD develop sarcopenia involving decreased levels of myofibrillar proteins, increased UPS, and oxidative stress, but not for impaired caloric intake or immobility.

Somatotropic Axis Dysfunction in Non-Alcoholic Fatty Liver Disease: Beneficial Hepatic and Systemic Effects of Hormone Supplementation.

BACKGROUND: Somatotropic axis dysfunction associated with non-alcoholic fatty liver disease (NAFLD) has potential multisystemic detrimental effects. Here, we analysed the effects of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) supplementation on liver histology, adipokine profile and muscle function in an NAFLD model. METHODS: C57BL/6 mice were fed with a high fat diet (HFD) for 12 weeks and were separated into three groups treated for 4 weeks with: (1) High fat diet (HFD) (n = 10); (2) HFD + GH 9 μg/g/d (n = 10); (3) HFD + IGF-1 0.02 µg/g/d (n = 9). A control group fed a chow diet was included (n = 6). Liver histology, liver triglycerides content, serum alanine aminotransferase (ALT) activity, adiponectin and leptin serum levels, in vivo muscle strength, tetanic force and muscle fibre cross-sectional area (CSA) were measured. RESULTS: HFD + GH and HFD + IGF-1 groups showed significantly lower ALT activity compared to HFD (p < 0.01). Liver triglyceride content in HFD + GH was decreased compared to HFD (p < 0.01). Histologic steatosis score was increased in HFD and HFD + GH group (p < 0.01), whereas HFD + IGF-1 presented no difference compared to the chow group (p = 0.3). HFD + GH group presented lower serum leptin and adiponectin levels compared to HFD. GH and IGF-1 supplementation therapy reverted HFD-induced reduction in muscle strength and CSA (sarcopenia). CONCLUSIONS: GH and IGF-1 supplementation induced significant improvement in liver steatosis, aminotransferases and sarcopenia in a diet-induced NAFLD model.

TGF-ß requires the activation of canonical and non-canonical signalling pathways to induce skeletal muscle atrophy.

The transforming growth factor type-beta (TGF-ß) induces skeletal muscle atrophy characterised by a decrease in the fibre's diameter and levels of myosin heavy chain (MHC), also as an increase of MuRF-1 expression. In addition, TGF-ß induces muscle atrophy by a mechanism dependent on reactive oxygen species (ROS). TGF-ß signals by activating both canonical Smad-dependent, and non-canonical signalling pathways such as ERK1/2, JNK1/2, and p38 MAPKs. However, the participation of canonical and non-canonical signalling pathways in the TGF-ß atrophic effect on skeletal muscle is unknown. We evaluate the impact of Smad and MAPK signalling pathways on the TGF-ß-induced atrophic effect in C2C12 myotubes. The results indicate that TGF-ß activates Smad2/3, ERK1/2 and JNK1/2, but not p38 in myotubes. The pharmacological inhibition of Smad3, ERK1/2 and JNK1/2 activation completely abolished the atrophic effect of TGF-ß. Finally, the inhibition of these canonical and non-canonical pathways did not decrease the ROS increment, while the inhibition of ROS production entirely abolished the phosphorylation of Smad3, ERK1/2 and JNK1/2. These results suggest that TGF-ß requires Smad3, ERK1/2 and JNK1/2 activation to produce skeletal muscle atrophy. Moreover, the induction of ROS by TGF-ß is an upstream event to canonical and non-canonical pathways.