Respiratory Abnormalities Research Articles

Respiratory Disease Detection using Convolutional Neural Networks and Audio Signal Analysis

This study investigates the application of respiratory audio signals for the detection of lung disorders, such as asthma, COPD, and pneumonia, utilizing convolutional neural networks (CNNs). Lung disorders frequently generate atypical noises such as wheezes, crackles, and stridor as a result of tracheal and pulmonary problems. Although manual inspection formerly enabled early detection, the intricacy of contemporary diseases demands more accurate diagnostic instruments. This research establishes a system that analyzes audio data, extracts features, and utilizes convolutional neural networks to categorize pulmonary disorders based on respiration sounds. Advanced methodologies such as digital stethoscopes and frequency modulation analysis are employed to segment and scrutinize lung sounds, facilitating the identification of respiratory abnormalities. The technology utilizes machine learning and AI to provide a non-invasive, economical method for identifying conditions such as pneumonia and interstitial lung disease. Despite limitations including hearing interference and data harmonization, this technology possesses significant potential to revolutionize early detection and remote monitoring of lung disorders, enhancing healthcare outcomes in both clinical and resource-limited environments.

Obstructive sleep apnoea and lung function, and their association with nocturnal hypoxemia: results from the Swedish CArdioPulmonary bioimage Study (SCAPIS) – a cross-sectional study

Obstructive sleep apnoea (OSA) and its associations with lung function.BackgroundOSA is highly prevalent and characterised by abnormal respiration during sleep. This large, population-based study aimed to investigate the associations between OSA and lung function in subjects aged 50–64 years.MethodThe population-based Swedish CArdioPulmonary bioimage Study includes information on anthropometry, comorbidities and spirometry. The current analysis included data from three centres (Gothenburg, Umeå and Uppsala) on whole-night respiratory polygraphy as a meta-analysis examining the overall effect size of lung function on sleep apnoea severity, expressed as ß-coefficient after stratifying for sex and adjusting for age, waist circumference and smoking status.ResultsData from9016participants (54%women, age58±4 years, body mass index27±4 kg/m2) with sleep recordings of good quality were included in the final analysis. Forced expiratory volume during1 s(FEV1) (ß=−0.10 (95% CI −0.16 to −0.03)),forced vital capacity(FVC) (−0.15 (−0.21 to −0.10)) anddiffusion capacity for carbon monoxide(DLCO) (−0.08 (−0.10 to −0.05)) were all negatively associated with theoxygen desaturation index(ODI) and also with per cent of registration with nocturnal oxygen saturation<90% FVC(−0.44 (−0.87 to −0.01)), FEV1(−0.86 (−1.36 to −0.36)) and DLCO(−0.47 (−0.60 to −0.35)). Additionally, a positive association was observed between FEV1(0.13 (0.05 to 0.22)) and DLCO(0.07 (0.04 to 0.09)) with the mean nocturnal saturation. There was a negative association between DLCOandapnoea-hypopnoea index, AHI, (ß=−0.04 (95% CI−0.06 to −0.03)), while no associations were found between FEV1or FVC and AHI.ConclusionIn OSA, lower lung function is more distinctly associated with the nocturnal hypoxic burden than AHI. Potential lung function impairment should be investigated in OSA patients with a high ODI relative to AHI.

Congenital pulmonary airway malformation in a cat.

Congenital structural anomalies of the lower airways of the respiratory tract are uncommon in cats. We describe here a case of cystic pulmonary lesions in a 6-wk-old domestic shorthair cat consistent with congenital pulmonary airway malformation (CPAM; formerly referred to as cystic adenomatoid malformation of the lung, or congenital pulmonary adenomatoid malformation; Stocker type II). CPAM is rarely reported in veterinary species and, to our knowledge, has not been reported in cats. In humans and veterinary species, individuals with CPAM (Stocker types I-IV) can be asymptomatic at birth but are predisposed to developing respiratory abnormalities that typically manifest clinically in the early years of life. We review the pathologic features of CPAM.

Profibrotic monocyte-derived alveolar macrophages are expanded in patients with persistent respiratory symptoms and radiographic abnormalities after COVID-19

Monocyte-derived alveolar macrophages drive lung injury and fibrosis in murine models and are associated with pulmonary fibrosis in humans. Monocyte-derived alveolar macrophages have been suggested to develop a phenotype that promotes lung repair as injury resolves. We compared single-cell and cytokine profiling of the alveolar space in a cohort of 35 patients with post-acute sequelae of COVID-19 who had persistent respiratory symptoms and abnormalities on a computed tomography scan of the chest that subsequently improved or progressed. The abundance of monocyte-derived alveolar macrophages, their gene expression programs, and the level of the monocyte chemokine CCL2 in bronchoalveolar lavage fluid positively associated with the severity of radiographic fibrosis. Monocyte-derived alveolar macrophages from patients with resolving or progressive fibrosis expressed the same set of profibrotic genes. Our findings argue against a distinct reparative phenotype in monocyte-derived alveolar macrophages, highlighting their utility as a biomarker of failed lung repair and a potential target for therapy.

Clinical application of flexible fiberoptic bronchoscopy in neonatal respiratory diseases

BackgroundRespiratory disease is a predominantly observed problem in neonates. Moreover, the application of flexible bronchoscopy in newborns is gradually increasing. This study aimed to investigate the value of bronchoscopy in neonates respiratory abnormalities and evaluate the safety of bronchoscopy application.MethodsClinical data and outcomes of 56 neonates who underwent flexible bronchoscopy were retrospectively analyzed. Correlations among indications for bronchoscopy, findings, and clinical diseases were assessed.ResultsA total of 56 neonates had a minimum weight of 1200 g at the time of bronchoscopy, while the minimum gestational age at birth was 26 + 1 weeks. A total of 22 cases (39.3%) had two or more clinical indications; the five most common indications were respiratory distress in 24 (42.9%), stridor in 22 (39.3%), pulmonary atelectasis in 10 (17.6%), feeding difficulty in 10 (17.6%), and difficult weaning from mechanical ventilation in 6 (10.7%) cases. A total of 13 types of abnormalities were detected in the respiratory tract. The most common abnormalities were laryngomalacia in 29 (59.2%), tracheobroncomalacia in 8 (16.3%), and vocal cord paralysis in 6 (12.2%) cases. Bronchoalveolar lavage was performed in 39 cases. Eight cases were diagnosed by bronchoscopy and then treated with surgery in the Thoracic Surgery/Otolaryngology Department; all of them were cured and discharged from the hospital after surgery. No serious complications, such as pneumothorax or shock, occurred in any of the children, of whom none died.ConclusionsFlexible bronchoscopy could play an important role in diagnosing and identifying respiratory disorders in neonates and be safely used with few serious complications.

A novel homozygous mutation in the DNAAF3 gene leads to severe asthenozoospermia and teratospermia.

Primary ciliary dyskinesia (PCD) is an autosomal recessive genetic disorder characterized by ultrastructural defects in the cilia or flagella of cells, causing respiratory abnormalities, sinusitis, visceral transposition, and male infertility. DNAAF3 plays an important role in the assembly and transportation of axonemal dynein complexes in cilia or flagella and has been shown to be associated with PCD. To date, only two cases of PCD with infertility associated with DNAAF3 mutations have been reported, and no mouse models for this gene have been successfully constructed. This study was conducted on an infertile Chinese male patient with a history of bronchitis. Examination of the patient's semen revealed severe asthenozoospermia and teratospermia. Whole exome sequencing revealed a new homozygous loss-of-function DNAAF3 mutation. CRISPR-Cas9 gene-editing technology was used to construct the same mutation in C57/B6 mice, revealing that homozygous C57/B6 mice were characterized by severe hydrocephalus and early death. The results of this study expand the mutation spectrum of DNAAF3 and confirm its correlation with PCD pathogenesis. This study provides new insights on the mechanisms underlying male infertility related to DNAAF3 mutation and PCD.

An IoT-based contactless neonatal respiratory monitoring system for neonatal care assistance in postpartum center

According to previous studies, one of the major causes of 20 % to 25 % of neonatal deaths is respiratory distress syndrome (RDS). Early identification, progressive monitoring, and treatment and/or management of neonatal RDS can substantially increase the rate of survival in neonates. However, global research indicates frequent shortages and burnout among nursing staff, especially in postpartum units, contributing to the difficulty in early identification of RDS in neonates. Clinicians currently use breathing sounds and frequency as key criteria in the Neonatal Resuscitation Program (NRP) for identifying and treating RDS. In practice, the monitoring of respiratory signal abnormalities relies on sensor patches, which frequently detach from the neonates’ slippery skin, leading to potential skin injuries and unstable signal reception. This paper presents an Internet of Things (IoT)-based contactless neonatal respiratory monitoring system that integrates computer vision (CV), beamforming microphone array (BFMA), and millimeter Wave (mmWave) radar, all connected to a cloud platform. Clinical trials revealed that CV-based neonatal feature identification achieved over 96 % accuracy within 40 cm to 120 cm. The neonatal breathing sound strengthening, utilized CV and BFMA, achieved an average sound-to-noise ratio (SNR) of 5.07 dB, and CV with mmWave radar reduced chest displacement signal error from 0.66 to 0.26 BPM. Additionally, survey results showed that doctors and clinical personnel were satisfied with the system's functionality and usability. This demonstrates the system's ability to assist in monitoring respiratory signals of swaddled neonates and in the early identification of neonatal RDS, with further applications in neonatal care at postpartum centers.

A Neural Basis for Mutant ATAXIN-1 Induced Respiratory Dysfunction in Mouse Models of Spinocerebellar Ataxia Type 1.

Spinocerebellar ataxia type 1 (SCA1), a dominantly inherited neurodegenerative disorder caused by an expanded trinucleotide repeat in the ATAXIN-1 (ATXN1) gene, is characterized by motor dysfunction, cognitive impairment, and death from compromised swallowing and respiration. To delineate specific cell types that contribute to respiratory dysfunction, we utilized the floxed conditional knock-in f-ATXN1 146Q/2Q mouse. Whole body plethysmography during spontaneous respiration and respiratory challenge showed that f-ATXN1 146Q/2Q mice exhibit a spontaneous respiratory phenotype characterized by elevated respiratory frequency, volumes, and respiratory output. Consequently, the ability of f-ATXN1 146Q/2Q mice to increase ventilation during the challenge is impaired. To investigate the role of mutant ATXN1 expression in neural and skeletal muscle lineages, f-ATXN1 146Q/2Q mice were bred to Nestin-Cre and Acta1-Cre mice respectively. These analyses revealed that the abnormal spontaneous respiration in f-ATXN1 146Q/2Q mice involved two aspects: a behavioral phenotype in which SCA1 mice exhibit increased motor activity during respiratory testing and functional dysregulation of central respiratory control centers. Both aspects of spontaneous respiration were partially ameliorated by removing mutant ATXN1 from neural, but not skeletal muscle, cell lineages.

Central and peripheral mechanisms underlying respiratory deficits in a mouse model of accelerated senescence.

Aging invariably decreases sensory and motor stimuli and affects several neuronal systems and their connectivity to key brain regions, including those involved in breathing. Nevertheless, further investigation is needed to fully comprehend the link between senescence and respiratory function. Here, we investigate whether a mouse model of accelerated senescence could develop central and peripheral respiratory abnormalities. Adult male Senescence Accelerated Mouse Prone 8 (SAMP8) and the control SAMR1 mice (10months old) were used. Ventilatory parameters were assessed by whole-body plethysmography, and measurements of respiratory input impedance were performed. SAMP8 mice exhibited a reduction in the density of neurokinin-1 receptor immunoreactivity in the entire ventral respiratory column. Physiological experiments showed that SAMP8 mice exhibited a decreased tachypneic response to hypoxia (FiO2 = 0.08; 10min) or hypercapnia (FiCO2 = 0.07; 10min). Additionally, the ventilatory response to hypercapnia increased further due to higher tidal volume. Measurements of respiratory mechanics in SAMP8 mice showed decreased static compliance (Cstat), inspiratory capacity (IC), resistance (Rn), and elastance (H) at different ages (3, 6, and 10months old). SAMP8 mice also have a decrease in contractile response to methacholine compared to SAMR1. In conclusion, our findings indicate that SAMP8 mice display a loss of the NK1-expressing neurons in the respiratory brainstem centers, along with impairments in both central and peripheral respiratory mechanisms. These observations suggest a potential impact on breathing in a senescence animal model.

Effect of positive allosteric modulation and orthosteric agonism of dopamine D2-like receptors on respiration in mouse models of Rett syndrome

Rett syndrome (RTT) is an autism spectrum disorder caused by loss-of-function mutations in the methyl-CPG-binding protein 2 (Mecp2) gene. Frequent apneas and irregular breathing are prevalent in RTT, and also occur in rodent models of the disorder, including Mecp2Bird and Mecp2R168X mice. Sarizotan, a serotonin 5-HT1a and dopamine D2-like receptor agonist, reduces the incidence of apneas and irregular breathing in mouse models of RTT (Abdala et al., 2014). Targeting the 5HT1a receptor alone also improves respiration in RTT mice (Levitt et al., 2013). However, the contribution of D2-like receptors in correcting these respiratory disturbances remains untested. PAOPA, a dopamine D2-like receptor positive allosteric modulator, and quinpirole, a dopamine D2-like receptor orthosteric agonist, were used in conjunction with whole-body plethysmography to evaluate whether activation of D2-like receptors is sufficient to improve breathing disturbances in female heterozygous Mecp2Bird/+ and Mecp2R168X/+ mice. PAOPA did not significantly change apnea incidence or irregularity score in RTT mice. PAOPA also had no effect on the ventilatory response to hypercapnia (7 % CO2). In contrast, quinpirole reduced apnea incidence and irregularity scores and improved the hypercapnic ventilatory response in Mecp2R168X/+ and Mecp2Bird/+ mice, while also reducing respiratory rate. These results suggest that D2-like receptors could contribute to the positive effects of sarizotan in the correction of respiratory abnormalities in Rett syndrome. However, positive allosteric modulation of D2-like receptors alone was not sufficient to evoke these effects.

Association of Obstructive Sleep Apnea with co-morbidities in smokers versus non-smokers - an observational study

Obstructive Sleep Apnea (OSA) and smoking are important global health issues that are widely prevalent. Both are independently associated with cardiovascular, respiratory, metabolic, neurological, psychiatric, and endocrinological abnormalities and cancer, leading to premature death. Whether coexistent OSA and smoking worsen multisystem abnormalities is inconclusive. Therefore, this study was done to find the association between OSA and other morbidities among smokers and non-smokers. The objectives of this study were i) to evaluate the association of OSA with co-morbidities in smokers and non-smokers and ii) to compare the severity of OSA in smokers and non-smokers.

Altered ventilatory responses to hypercapnia-hypoxia challenges in a preclinical SUDEP model involve orexin neurons

Failure to recover from repeated hypercapnia and hypoxemia (HH) challenges caused by severe GCS and postictal apneas may contribute to sudden unexpected death in epilepsy (SUDEP). Our previous studies found orexinergic dysfunction contributes to respiratory abnormalities in a preclinical model of SUDEP, Kcna1−/− mice. Here, we developed two gas challenges consisting of repeated HH exposures and used whole body plethysmography to determine whether Kcna1−/− mice have detrimental ventilatory responses. Kcna1−/− mice exhibited an elevated ventilatory response to a mild repeated hypercapnia-hypoxia (HH) challenge compared to WT. Moreover, 71% of Kcna1−/− mice failed to survive a severe repeated HH challenge, whereas all WT mice recovered. We next determined whether orexin was involved in these differences. Pretreating Kcna1−/− mice with a dual orexin receptor antagonist rescued the ventilatory response during the mild challenge and all subjects survived the severe challenge. In ex vivo extracellular recordings in the lateral hypothalamus of coronal brain slices, we found reducing pH either inhibits or stimulates putative orexin neurons similar to other chemosensitive neurons; however, a significantly greater percentage of putative orexin neurons from Kcna1−/−mice were stimulated and the magnitude of stimulation was increased resulting in augmentation of the calculated chemosensitivity index relative to WT. Collectively, our data suggest that increased chemosensitive activity of orexin neurons may be pathologic in the Kcna1−/− mouse model of SUDEP, and contribute to elevated ventilatory responses. Our preclinical data suggest that those at high risk for SUDEP may be more sensitive to HH challenges, whether induced by seizures or other means; and the depth and length of the HH exposure could dictate the probability of survival.

MmWave-RM: A Respiration Monitoring and Pattern Classification System Based on mmWave Radar.

Breathing is one of the body's most basic functions and abnormal breathing can indicate underlying cardiopulmonary problems. Monitoring respiratory abnormalities can help with early detection and reduce the risk of cardiopulmonary diseases. In this study, a 77 GHz frequency-modulated continuous wave (FMCW) millimetre-wave (mmWave) radar was used to detect different types of respiratory signals from the human body in a non-contact manner for respiratory monitoring (RM). To solve the problem of noise interference in the daily environment on the recognition of different breathing patterns, the system utilised breathing signals captured by the millimetre-wave radar. Firstly, we filtered out most of the static noise using a signal superposition method and designed an elliptical filter to obtain a more accurate image of the breathing waveforms between 0.1 Hz and 0.5 Hz. Secondly, combined with the histogram of oriented gradient (HOG) feature extraction algorithm, K-nearest neighbours (KNN), convolutional neural network (CNN), and HOG support vector machine (G-SVM) were used to classify four breathing modes, namely, normal breathing, slow and deep breathing, quick breathing, and meningitic breathing. The overall accuracy reached up to 94.75%. Therefore, this study effectively supports daily medical monitoring.

Persistence of lung structural and functional alterations at one year post-COVID-19 is associated with increased serum PD-L2 levels and altered CD4/CD8 ratio.

Persistent respiratory symptoms and lung abnormalities post-COVID-19 are public health problems. This study evaluated biomarkers to stratify high-risk patients to the development or persistence of post-COVID-19 interstitial lung disease. One hundred eighteen patients discharged with residual lung abnormalities compatible with interstitial lung disease (COVID-ILD patients) after a severe COVID-19 were followed for 1 year (post-COVID-ILD patients). Physical examination, pulmonary function tests, and chest high-resolution computed tomography (HRCT) were performed. Soluble forms (s) of PD-L1, PD-L2, TIM-3, and GAL-9 were evaluated in serum and cell culture supernatant, as well as T-cells subsets and the transmembrane expression of PD-L1 and PD-L2 on the cell surface. Eighty percent of the post-COVID-ILD patients normalized their lung function at 1-year follow-up, 8% presented COVID-independent ILD, and 12% still showed functional and HRCT alterations. PD-L2 levels were heterogeneous during acute COVID-19 (aCOVID); patients who increased (at least 30%) their sPD-L2 levels at 1 year post-COVID-19 and exhibited altered CD4/CD8 ratio showed persistence of chest tomographic and functional alterations. By contrast, patients who decreased sPD-L2 displayed a complete lung recovery. sPD-L1, sTIM-3, and sGAL-9 increased significantly during aCOVID and decreased in all patients after 1-year follow-up. Increased sPD-L2 and an altered CD4/CD8 ratio after 12 months of aCOVID are associated with the persistence of lung lesions, suggesting that they may contribute to lung damage post-COVID-19.

Pulmonary hypertension in patients affected by sleep-related breathing disorders: up to date from the literature.

Sleep-related breathing disorders (SBD) are conditions of abnormal and difficult respiration during sleep, including chronic snoring, obstructive sleep apnea (OSA), central sleep apnea (CSA), sleep-related hypoventilation disorders and sleep-related hypoxemia. Some of them have a limited impact on health, but others (e.g., OSA) can have serious consequences, because of their dangerous effects on sleep and the hematic balance of oxygen and carbon dioxide. According to several population-based studies, prevalence of OSA is relatively high, approximately 3-7% for adult males and 2-5% for adult females in the general population. However, methodological differences and difficulties in characterizing this syndrome yielded to variability in estimates. Moreover, it is estimated that only about 40% of patients with OSA are diagnosed, which can lead to underestimation of disease prevalence. OSA is directly correlated with age and male sex and to risk factors such as obesity. Several studies found that OSA is associated with an increased risk of diabetes, some cancer types, cardiovascular and cerebrovascular diseases, such as hypertension, coronary artery disease and stroke. Pulmonary hypertension (PH), a noted cardiovascular disease, is significantly associated with sleep-related breathing disorders and lot of scientific studies published in the literature demonstrated a strong link between these conditions and the development of pulmonary hypertension PH. PH is relatively less common than sleep-related breathing disorders. The purpose of this systematic review is to analyze both the current knowledge around the consequences that SBD may have on pulmonary hemodynamics and the effects resulting from pharmacological and non-pharmacological treatments of SDB on PH.

The Cardio-Respiratory Mechanisms Involved in the Diving Response Adaptation and Breath-Hold Training Effects in Freedivers

This review aims to explore the cardiovascular and respiratory mechanisms involved in the training effects of the diving response adaptation and to determine the adaptive changes during apnoea and breath-hold training in breath-hold divers. A sounder theoretical knowledge of these critical aspects is necessary to be able to understand the oxygen-conserving mechanism of the diving response, and the apnoea-induced cardiorespiratory adjustments involved in enriching the science of respiratory physiology and the development of breath-hold training and ability. These insights may contribute to understanding the pathophysiology of respiratory abnormalities and dysfunctional breathing in humans. Furthermore, it may facilitate the development of efficacious interventions to increase breath-holding ability, and sports performance, as well as assist with the management and treatment of various physiological and psychological conditions. This review will be presented in four separate sections. Section one will describe the diving response and its physiology. Section two will explore the cardio-respiratory mechanisms of the diving response. Section three will discuss the adaptive changes associated with breath-hold training and/or apnoea training, as well as the associated cardio-respiratory adaptions. Section four will explore the clinical applications and implications of the diving response.

Brachycephalic obstructive airway syndrome: a respiratory review

This article reviews the pathogenesis, diagnosis and therapeutic options for the respiratory aspects of brachycephalic obstructive airway syndrome. Brachycephalic obstructive airway syndrome is a condition estimated to affect around 50% of the brachycephalic dog population, which, over recent decades, has seen a meteoric rise in popularity and ownership. Several primary and secondary respiratory abnormalities that can compromise the respiratory capacity of these patients should be considered. Diagnosis primarily takes the form of clinical examination and the use of an exercise tolerance test, with other diagnostics acting as a useful adjunct in fully detailing the abnormalities present. Treatments are mainly focussed on increasing the amount of space within the upper respiratory tract through removal of various primary and secondary anatomical abnormalities; however, the optimal methods are yet to be identified. While understanding of these breeds' respiratory issues has increased among owners and the veterinary profession, there are still many challenges and unknowns in the management of these patients. It is important veterinary professionals take an active approach to these patients and are able to effectively communicate which are affected in order to maximise the welfare of this cohort and uphold their ethical responsibilities to them.

Histology Atlas of the Developing Mouse Respiratory System From Prenatal Day 9.0 Through Postnatal Day 30.

Respiratory diseases are one of the leading causes of death and disability around the world. Mice are commonly used as models of human respiratory disease. Phenotypic analysis of mice with spontaneous, congenital, inherited, or treatment-related respiratory tract abnormalities requires investigators to discriminate normal anatomic features of the respiratory system from those that have been altered by disease. Many publications describe individual aspects of normal respiratory tract development, primarily focusing on morphogenesis of the trachea and lung. However, a single reference providing detailed low- and high-magnification, high-resolution images of routine hematoxylin and eosin (H&E)-stained sections depicting all major structures of the entire developing murine respiratory system does not exist. The purpose of this atlas is to correct this deficiency by establishing one concise reference of high-resolution color photomicrographs from whole-slide scans of H&E-stained tissue sections. The atlas has detailed descriptions and well-annotated images of the developing mouse upper and lower respiratory tracts emphasizing embryonic days (E) 9.0 to 18.5 and major early postnatal events. The selected images illustrate the main structures and events at key developmental stages and thus should help investigators both confirm the chronological age of mouse embryos and distinguish normal morphology as well as structural (cellular and organ) abnormalities.

A transcriptional enhancer regulates cardiac maturation.

Cardiomyocyte maturation is crucial for generating adult cardiomyocytes and the application of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). However, regulation at the cis-regulatory element level and its role in heart disease remain unclear. Alpha-actinin 2 (ACTN2) levels increase during CM maturation. In this study, we investigated a clinically relevant, conserved ACTN2 enhancer's effects on CM maturation using hPSC and mouse models. Heterozygous ACTN2 enhancer deletion led to abnormal CM morphology, reduced function and mitochondrial respiration. Transcriptomic analyses in vitro and in vivo showed disrupted CM maturation and upregulated anabolic mammalian target for rapamycin (mTOR) signaling, promoting senescence and hindering maturation. As confirmation, ACTN2 enhancer deletion induced heat shock protein 90A expression, a chaperone mediating mTOR activation. Conversely, targeting the ACTN2 enhancer via enhancer CRISPR activation (enCRISPRa) promoted hPSC-CM maturation. Our studies reveal the transcriptional enhancer's role in cardiac maturation and disease, offering insights into potentially fine-tuning gene expression to modulate cardiomyocyte physiology.

Cellular and molecular alterations to muscles and neuromuscular synapses in a mouse model of MEGF10-related myopathy

Loss-of-function mutations in MEGF10 lead to a rare and understudied neuromuscular disorder known as MEGF10-related myopathy. There are no treatments for the progressive respiratory distress, motor impairment, and structural abnormalities in muscles caused by the loss of MEGF10 function. In this study, we deployed cellular and molecular assays to obtain additional insights about MEGF10-related myopathy in juvenile, young adult, and middle-aged Megf10 knockout (KO) mice. We found fewer muscle fibers in juvenile and adult Megf10 KO mice, supporting published studies that MEGF10 regulates myogenesis by affecting satellite cell differentiation. Interestingly, muscle fibers do not exhibit morphological hallmarks of atrophy in either young adult or middle-aged Megf10 KO mice. We next examined the neuromuscular junction (NMJ), in which MEGF10 has been shown to concentrate postnatally, using light and electron microscopy. We found early and progressive degenerative features at the NMJs of Megf10 KO mice that include increased postsynaptic fragmentation and presynaptic regions not apposed by postsynaptic nicotinic acetylcholine receptors. We also found perisynaptic Schwann cells intruding into the NMJ synaptic cleft. These findings strongly suggest that the NMJ is a site of postnatal pathology in MEGF10-related myopathy. In support of these cellular observations, RNA-seq analysis revealed genes and pathways associated with myogenesis, skeletal muscle health, and NMJ stability dysregulated in Megf10 KO mice compared to wild-type mice. Altogether, these data provide new and valuable cellular and molecular insights into MEGF10-related myopathy.