Identification of enhancer regulatory elements that direct epicardial gene expression during zebrafish heart regeneration.

The epicardium is a mesothelial tissue layer that envelops the heart. Cardiac injury activates dynamic gene expression programs in epicardial tissue, which in zebrafish enables subsequent regeneration through paracrine and vascularizing effects. To identify tissue regeneration enhancer elements (TREEs) that control injury-induced epicardial gene expression during heart regeneration, we profiled transcriptomes and chromatin accessibility in epicardial cells purified from regenerating zebrafish hearts. We identified hundreds of candidate TREEs, which are defined by increased chromatin accessibility of non-coding elements near genes with increased expression during regeneration. Several of these candidate TREEs were incorporated into stable transgenic lines, with five out of six elements directing injury-induced epicardial expression but not ontogenetic epicardial expression in larval hearts. Whereas two independent TREEs linked to the gene gnai3 showed similar functional features of gene regulation in transgenic lines, two independent ncam1a-linked TREEs directed distinct spatiotemporal domains of epicardial gene expression. Thus, multiple TREEs linked to a regeneration gene can possess either matching or complementary regulatory controls. Our study provides a new resource and principles for understanding the regulation of epicardial genetic programs during heart regeneration. This article has an associated 'The people behind the papers' interview.

Methods for dynamic and whole volume imaging of the zebrafish heart.

Tissue development and regeneration are dynamic processes involving complex cell migration and cell-cell interactions. We have developed a protocol for complementary time-lapse and three-dimensional (3D) imaging of tissue for developmental and regeneration studies which we apply here to the zebrafish cardiac vasculature. 3D imaging of fixed specimens is used to first define the subject at high resolution then live imaging captures how it changes dynamically. Hearts from adult and juvenile zebrafish are extracted and cleaned in preparation for the different imaging modalities. For whole-mount 3D confocal imaging, single or multiple hearts with native fluorescence or immuno-labeling are prepared for stabilization or clearing, and then imaged. For live imaging, hearts are placed in a prefabricated fluidic device and set on a temperature-controlled microscope for culture and imaging over several days. This protocol allows complete visualization of morphogenic processes in a 3D context and provides the ability to follow cell behaviors to complement in vivo and fixed tissue studies. This culture and imaging protocol can be applied to different cell and tissue types. Here, we have used it to observe zebrafish coronary vasculature and the migration of coronary endothelial cells during heart regeneration.

leptin b and its regeneration enhancer illustrate the regenerative features of zebrafish hearts.

BACKGROUND: Zebrafish possess a remarkable regenerative capacity, which is mediated by the induction of various genes upon injury. Injury-dependent transcription is governed by the tissue regeneration enhancer elements (TREEs). Here, we utilized leptin b (lepb), an injury-specific factor, and its TREE to dissect heterogeneity of noncardiomyocytes (CMs) in regenerating hearts. RESULTS: Our single-cell RNA sequencing (scRNA-seq) analysis demonstrated that the endothelium/endocardium(EC) is activated to induce distinct subpopulations upon injury. We demonstrated that lepb can be utilized as a regeneration-specific marker to subset injury-activated ECs. lepb+ ECs robustly induce pro-regenerative factors, implicating lepb+ ECs as a signaling center to interact with other cardiac cells. Our scRNA-seq analysis identified that lepb is also produced by subpopulation of epicardium (Epi) and epicardium-derived cells (EPDCs). To determine whether lepb labels injury-emerging non-CM cells, we tested the activity of lepb-linked regeneration enhancer (LEN) with chromatin accessibility profiles and transgenic lines. While nondetectable in uninjured hearts, LEN directs EC and Epi/EPDC expression upon injury. The endogenous LEN activity was assessed using LEN deletion lines, demonstrating that LEN deletion abolished injury-dependent expression of lepb, but not other nearby genes. CONCLUSIONS: Our integrative analyses identify regeneration-emerging cell-types and factors, leading to the discovery of regenerative features of hearts.

Utility of Dual-Layer Spectral Detector CTA to Characterize Carotid Atherosclerotic Plaque Components: An Imaging-Histopathology Comparison in Patients Undergoing Endarterectomy.

BACKGROUND. The composition of noncalcified portions of carotid atherosclerotic plaque is an important marker of plaque vulnerability and ischemia risk. OBJECTIVE. The purpose of this study was to assess the utility of dual-layer spectral detector CTA (DLCTA) parameters for characterization of carotid plaque components with histologic results from carotid endarterectomy as the reference. METHODS. Seven patients (five men, two women; mean age, 61.6 ± 8.5 [SD] years) with carotid plaque awaiting carotid endarterectomy were prospectively enrolled and underwent preoperative supraaortic DLCTA. A neuroradiologist and pathologist performed joint slice-by-slice review of histologic slices of resected plaques and CTA images. With the use of anatomic landmarks, ROIs were placed on noncalcified components (lipid-rich necrotic core [LRNC], intraplaque hemorrhage [IPH], fibrous tissue, loose matrix) on CTA images and compared with corresponding histologic slices. For each ROI, attenuation was recorded for conventional polyenergetic images (CTPI) and virtual monoenergetic images with energy ranging from 40 to 140 keV (CT40-140keV), attenuation spectrum curve slope was calculated, and Z-effective value (representing effective atomic number) was recorded. DLCTA parameters were compared among plaque components. RESULTS. Seven plaques with a total of 65 slices and 364 ROIs (159 fibrous tissue, 96 LRNC, 86 loose matrix, 23 IPH) were analyzed. All parameters (CTPI, CT40-140keV, slope from 40 to 140 keV, Z-effective value) had significant differences between LRNC and the other components (all p < .001). For example, mean CTPI was 37.1 ± 15.1 HU for LRNC, 58.4 ± 21.6 HU for IPH, 69.7 ± 20.5 HU for fibrous tissue, and 69.6 ± 19.6 HU for loose matrix. Mean CT40keV was 28.1 ± 36.7 HU for LRNC, 87.5 ± 48.9 HU for IPH, 106.3 ± 47.5 HU for fibrous tissue, and 102.6 ± 48.0 HU for loose matrix. AUC for differentiating LRNC from other components was highest (0.945) for CT40kev and decreased with higher energy; AUC for CTPI was 0.908. CT40kev also had highest accuracy (90.4%); at a cutoff of 55.7 HU, CT40kev had 88.5% sensitivity and 91.0% specificity. For differentiating IPH from fibrous tissue and loose matrix, AUC was highest at 0.652 for CTPI and 0.645 for CT40kev. CONCLUSION. DLCTA showed strong performance in differentiating LRNC from other noncalcified plaque components; CT40kev had highest accuracy, outperforming CTPI. CLINICAL IMPACT. DLCTA parameters may help characterize carotid plaque composition as a marker of vulnerable plaque and ischemia risk.

Diagnostic accuracy of cardiopulmonary ultrasound for pulmonary embolism: A systematic review and meta-analysis.

BACKGROUND: Cardiopulmonary ultrasound has shown varying results in the diagnosis of pulmonary embolism patients around the world. Hence, the current review was done to assess the diagnostic accuracy of cardiopulmonary ultrasound for diagnosis of pulmonary embolism among suspected patients. METHODS: We conducted a systematic search for all studies reporting the diagnostic accuracy of cardiopulmonary ultrasound for pulmonary embolism in the databases of MEDLINE, EMBASE, MEDLINE, SCOPUS, and Cochrane library from inception till May 2021. Meta-analysis was performed using STATA software "midas" package. RESULTS: Ten studies with 4216 patients were included. The pooled sensitivity was 77% (95% CI, 50-92%) and specificity was 99% (95% CI, 97-100%), respectively. The pooled DOR was 382 (95% CI, 77-1883). Pooled LRP was 90 (95% CI, 24-326) and pooled LRN was .23 (.09-.58). There was significant heterogeneity found with the outcome with significant chi-square test and I2 statistic > 75%. CONCLUSION: Cardiopulmonary ultrasound has the ability to be used as an adjunct to CTPA especially in resource constrained settings. Further reviews comparing multiple non-invasive imaging modalities are required to pick the best tool for diagnosis of pulmonary embolism.

Histological validation of simultaneous non-contrast angiography and intraplaque hemorrhage imaging (SNAP) for characterizing carotid intraplaque hemorrhage.

OBJECTIVES: This study sought to validate the performance of simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) imaging in characterizing carotid IPH by histology. METHODS: Thirty-five patients with carotid atherosclerotic disease (symptomatic 50-70% stenosis or > 70% stenosis) scheduled for carotid endarterectomy underwent 3.0-T carotid MR imaging by acquiring SNAP and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequences. Presence and area of IPH were separately evaluated on SNAP and MP-RAGE images. Presence and area of IPH were also assessed on histology. Agreement between SNAP/MP-RAGE and histology was determined in identify and quantify IPH using Cohen kappa, Spearman correlation, and Bland-Altman analyses. RESULTS: Of all 35 patients (mean age: 63.1 ± 8.8 years; 27 males), 128 slices with successful registration were eligible for analysis. The accuracy, sensitivity, specificity, and positive and negative predictive values were 86.7%, 85%, 89.6%, 93.2%, and 78.2% for SNAP, and 76.6%, 75%, 79.2%, 85.7%, and 65.5% for MP-RAGE in identification of IPH, respectively. In identification of IPH, the kappa value between SNAP and histology and between MP-RAGE and histology was 0.725 and 0.520, respectively. The correlation between SNAP and histology (r = 0.805, p < 0.001) was stronger than that between MP-RAGE and histology (r = 0.637, p < 0.001) in measuring IPH area. Bland-Altman analysis showed that, in measuring IPH area, the bias of SNAP (1.4 mm2, 95% CI: - 0.016 to 2.883) was smaller than that of MP-RAGE (1.7 mm2, 95% CI: - 0.039 to 3.430) compared with histology. CONCLUSIONS: This validation study by histology demonstrates that SNAP sequence better identifies and quantifies carotid intraplaque hemorrhage compared with traditional MP-RAGE sequence. KEY POINTS: • SNAP imaging showed better agreement with histology compared with MP-RAGE imaging, especially for the IPHs with small size. • SNAP sequence is a more effective tool to identify and quantify carotid IPH than traditional sequence of MP-RAGE that can help clinicians to optimizing the treatment strategy. • The plaque components of rich lipid pools or loose matrix and chronic/old IPH (cholesterol crystals) can lead to false positive and false negative results in SNAP and MP-RAGE imaging for identifying IPH.

Epicardial regeneration is guided by cardiac outflow tract and Hedgehog signalling.

In response to cardiac damage, a mesothelial tissue layer enveloping the heart called the epicardium is activated to proliferate and accumulate at the injury site. Recent studies have implicated the epicardium in multiple aspects of cardiac repair: as a source of paracrine signals for cardiomyocyte survival or proliferation; a supply of perivascular cells and possibly other cell types such as cardiomyocytes; and as a mediator of inflammation. However, the biology and dynamism of the adult epicardium is poorly understood. To investigate this, we created a transgenic line to ablate the epicardial cell population in adult zebrafish. Here we find that genetic depletion of the epicardium after myocardial loss inhibits cardiomyocyte proliferation and delays muscle regeneration. The epicardium vigorously regenerates after its ablation, through proliferation and migration of spared epicardial cells as a sheet to cover the exposed ventricular surface in a wave from the chamber base towards its apex. By reconstituting epicardial regeneration ex vivo, we show that extirpation of the bulbous arteriosus-a distinct, smooth-muscle-rich tissue structure that distributes outflow from the ventricle-prevents epicardial regeneration. Conversely, experimental repositioning of the bulbous arteriosus by tissue recombination initiates epicardial regeneration and can govern its direction. Hedgehog (Hh) ligand is expressed in the bulbous arteriosus, and treatment with a Hh signalling antagonist arrests epicardial regeneration and blunts the epicardial response to muscle injury. Transplantation of Sonic hedgehog (Shh)-soaked beads at the ventricular base stimulates epicardial regeneration after bulbous arteriosus removal, indicating that Hh signalling can substitute for the influence of the outflow tract. Thus, the ventricular epicardium has pronounced regenerative capacity, regulated by the neighbouring cardiac outflow tract and Hh signalling. These findings extend our understanding of tissue interactions during regeneration and have implications for mobilizing epicardial cells for therapeutic heart repair.

Quantitative evaluation of carotid atherosclerotic vulnerable plaques using in vivo T1 mapping cardiovascular magnetic resonaonce: validation by histology.

BACKGROUND: It has been proved that multi-contrast cardiovascular magnetic resonance (CMR) vessel wall imaging could be used to characterize carotid vulnerable plaque components according to the signal intensity on different contrast images. The signal intensity of plaque components is mainly dependent on the values of T1 and T2 relaxation. T1 mapping recently showed a potential in identifying plaque components but it is not well validated by histology. This study aimed to validate the usefulness of in vivo T1 mapping in assessing carotid vulnerable plaque components by histology. METHODS: Thirty-four subjects (mean age, 64.0 ± 8.9 years; 26 males) with carotid plaques referred to carotid endarterectomy were prospectively enrolled and underwent 3 T CMR imaging from May 2017 to October 2017. The T1 values of intraplaque hemorrhage (IPH), necrotic core (NC) and loose matrix (LM) which were identified on multi-contrast vessel wall images or histology were measured on in-vivo T1 mapping. The IPHs were divided into two types based on the proportion of the area of fresh hemorrhage on histology. The T1 values of different plaque components were compared using Mann-Whitney U test and the agreement between T1 mapping and histology in identifying and quantifying IPH was analyzed with Cohen's Kappa and intraclass correlation coefficient (ICC). RESULTS: Of 34 subjects, 19 had histological specimens matched with CMR imaging. The mean T1 values of IPH (651 ± 253 ms), NC (1161 ± 182 ms) and LM (1447 ± 310 ms) identified by histology were significantly different. The T1 values of Type 1 IPH were significantly shorter than that of Type 2 IPH (456 ± 193 ms vs. 775 ± 205 ms, p < 0.001). Moderate to excellent agreement was found in identification (kappa = 0.51, p < 0.001), classification (kappa = 0.40, p = 0.028) and segmentation (ICC = 0.816, 95% CI 0.679-0.894) of IPHs between T1 mapping and histology. CONCLUSIONS: The T1 values of carotid plaque components, particularly for intraplaque hemorrhage, are differentiable, and the stage of intraplaque hemorrhage can be classified according to T1 values, suggesting the potential capability of assessment of vulnerable plaque components by T1 mapping.

Health risk assessment and bioaccessibilities of heavy metals for children in soil and dust from urban parks and schools of Jiaozuo, China.

Urban parks and schools sever as the mainly activity areas for children, but risk assessment posed by heavy metals (HMs) from soil and dust in these area has rarely been investigated. In this study, six urban parks and seven schools in Jiaozuo, China, were taken as research objects to understand the contamination level and bioaccessibility of HMs from soil and dust in urban parks and schools. The results indicated that Zn, Cu, Pb, Cd, As, Ni and Co from soil and dust were above the background values, especially Zn and Cd in dust, and As and Cd in soil. Serious Cd pollution was discovered, and respective Cd concentrations in soil and dust were 17.83 and 7.52 times the background value. Additionally, the average concentration and bioaccessibility of Zn, Mn, Pb, Cd, Cr, Ni and Co in dust were both higher than in soil. High concentration and high bioaccessibility of HMs in dust suggested that HMs contamination were serious and universal in Jiaozuo. The concentrations of most HMs were higher in the gastric phase, except for Cu and Cd which remained higher in the intestinal phase. Both in the gastric phase and intestinal phase, Mn, As and Cd in soil and dust both have high bioaccessibility which all exceed 10%. The carcinogenic and non-carcinogenic risks base on the total HMs for children (soil: 7.93, 1.96E-05; dust: 6.44, 3.58E-05) were greater than those for adults (soil: 6.35E-01, 1.32E-05; dust: 5.06E-01, 2.42E-05), and urban parks and schools posed high potential risk for children. Therefore, assessment the risk posed by HMs contamination of soil and dust in urban parks and schools is vital and urgent for children.

Multicolor mapping of the cardiomyocyte proliferation dynamics that construct the atrium.

The orchestrated division of cardiomyocytes assembles heart chambers of distinct morphology. To understand the structural divergence of the cardiac chambers, we determined the contributions of individual embryonic cardiomyocytes to the atrium in zebrafish by multicolor fate-mapping and we compare our analysis to the established proliferation dynamics of ventricular cardiomyocytes. We find that most atrial cardiomyocytes become rod-shaped in the second week of life, generating a single-muscle-cell-thick myocardial wall with a striking webbed morphology. Inner pectinate myofibers form mainly by direct branching, unlike delamination events that create ventricular trabeculae. Thus, muscle clones assembling the atrial chamber can extend from wall to lumen. As zebrafish mature, atrial wall cardiomyocytes proliferate laterally to generate cohesive patches of diverse shapes and sizes, frequently with dominant clones that comprise 20-30% of the wall area. A subpopulation of cardiomyocytes that transiently express atrial myosin heavy chain (amhc) contributes substantially to specific regions of the ventricle, suggesting an unappreciated level of plasticity during chamber formation. Our findings reveal proliferation dynamics and fate decisions of cardiomyocytes that produce the distinct architecture of the atrium.

Single epicardial cell transcriptome sequencing identifies Caveolin 1 as an essential factor in zebrafish heart regeneration.

In contrast to mammals, adult zebrafish have a high capacity to regenerate damaged or lost myocardium through proliferation of cardiomyocytes spared from damage. The epicardial sheet covering the heart is activated by injury and aids muscle regeneration through paracrine effects and as a multipotent cell source, and has received recent attention as a target in cardiac repair strategies. Although it is recognized that epicardium is required for muscle regeneration and itself has high regenerative potential, the extent of cellular heterogeneity within epicardial tissue is largely unexplored. Here, we performed transcriptome analysis on dozens of epicardial lineage cells purified from zebrafish harboring a transgenic reporter for the pan-epicardial gene tcf21. Hierarchical clustering analysis suggested the presence of at least three epicardial cell subsets defined by expression signatures. We validated many new pan-epicardial and epicardial markers by alternative expression assays. Additionally, we explored the function of the scaffolding protein and main component of caveolae, caveolin 1 (cav1), which was present in each epicardial subset. In BAC transgenic zebrafish, cav1 regulatory sequences drove strong expression in ostensibly all epicardial cells and in coronary vascular endothelial cells. Moreover, cav1 mutant zebrafish generated by genome editing showed grossly normal heart development and adult cardiac anatomy, but displayed profound defects in injury-induced cardiomyocyte proliferation and heart regeneration. Our study defines a new platform for the discovery of epicardial lineage markers, genetic tools, and mechanisms of heart regeneration.

Risk Factors Associated with Infusion Reactions to Infliximab in Chinese Patients with Inflammatory Bowel Disease: A Large Single-Center Study.

BACKGROUND This study investigated the risk factors of infliximab (IFX)-related infusion reactions (IR) in Chinese patients with inflammatory bowel disease (IBD). MATERIAL AND METHODS The medical records of 330 consecutive IBD patients treated with IFX between 2009 and 2017 were reviewed. The incidence of IR and adverse effects were recorded in detail, and the potential risk factors related to IR were analyzed by univariate and logistic regression analysis. RESULTS The 330 patients received a total of 2108 IFX infusions, with a median follow-up of 29 months. Eighteen patients (5.5%) experienced IR: 15 were immediate (2 severe) and 3 were late (0 severe). The patients who were treated with episodic IFX without concomitant IM therapy and at the 2nd IFX series (all P<0.001) had higher incidence of IR. Logistic regression revealed the 2nd IFX treatment series (OR=0.017, P<0.001) and episodic use of IFX (OR=0.113, P<0.001) as the significant predictors. Antibodies against infliximab (ATI) were highly positive in 10 of 14 patients (71%) with IR. Sixty-seven percent of patients finished infusions after IR through appropriate management. CONCLUSIONS IFX infusions were accompanied by IR in about 5% of Chinese IBD patients. Severe IR was rare. The patients with the 2nd series or episodic use of IFX should be monitored closely during infusion.

Exosomes from Adipose-Derived Stem Cells Promotes VEGF-C-Dependent Lymphangiogenesis by Regulating miRNA-132/TGF-ß Pathway.

BACKGROUND/AIMS: Lymphangiogenesis plays an important role in the pathogenesis of inflammatory bowel diseases (IBD), and vascular endothelial growth factor-C (VEGF-C) is a powerful lymphangiogenic factor. Adipose-derived stem cells (ADSCs) are a promising therapeutic modality for several diseases because ADSCs secret growth factors and exosomes, which modulate hostile microenvironments affected by diseases. However, the effect of exosomes on VEGF-C-dependent lymphangiogenesis and its mechanism remain unclear. METHODS: ADSCs were cultured in media with or without recombinant VEGF-C and exosomes were extracted from conditioned medium (CM). Lymphatic endothelial cells (LECs) were treated with ADSCs-derived exosomes, then proliferation, migration and tube formation of LECs were assayed using cell counting Kit-8 (CCK-8), transwell chamber inserts and matrigel-based tube formation assay respectively. RESULTS: We identified significantly higher levels of miR-132 in exosomes isolated from VEGF-C-treated ADSCs (ADSCs/VEGF-C) than in those from ADSCs control. miR-132 was directly transferred from ADSCs to the LECs by the mediation of exosomes. The exosomes from ADSCs/VEGF-C promoted LECs proliferation, migration, and tube formation more potently than the exosomes from ADSCs, whereas pretreatment of ADSCs with miR-132 inhibitor attenuates VEGF-C-dependent lymphangiogenic response. Finally we reveal that miR-132 promotes lymphangiogenic response by directly targeting Smad-7 and regulating TGF-ß/Smad signaling. CONCLUSION: These data provide new insights into the role of ADSCs-derived exosomes as an important player in VEGF-C-dependent lymphangiogenesis.

The polymorphism of rs6505162 in the MIR423 coding region and recurrent pregnancy loss.

Although the relationship between polymorphisms in microRNAs (miRNAs) and recurrent pregnancy loss (RPL) has been studied, there is very little data available in the literature. In the present study, we scanned 55 potentially functional polymorphisms in the miRNA coding region in Chinese women with unexplained RPL (URPL; no. 2011-10). The rs6505162 C>A in the MIR423 coding region was found to be significantly associated with the occurrence of human URPL. The rare A allele contributed to an increase in the expression of mature MIR423. C to A substitution in the polymorphism rs6505162 in pre-MIR423 repressed cell proliferation and migratory capacity. Further investigations showed that MIR423 could inversely regulate the expression of proliferation-associated 2 group 4 (PA2G4) by binding the 3'-UTR of PA2G4. Dual-luciferase assay indicated that the A allele in the polymorphism rs6505162 could more effectively suppress the expression of PA2G4 than the C allele could. Collectively, the present data suggest that rs6505162 C>A in pre-MIR423 may contribute to the genetic predisposition to RPL by disrupting the production of mature MIR423 and its target gene, which consequently interferes with MIR423 functioning.

MiR199a is implicated in embryo implantation by regulating Grb10 in rat.

MiR199a was found to be differentially expressed in rat uteri between the prereceptive and receptive phase via microRNA (miRNA) microarray analysis in our previous study. However, the role of miR199a in rat embryo implantation remained unknown. In the study, northern blot results showed that the expression levels of miR199a were higher on gestation days 5 and 6 (g.d.5-6) in rat uteri than on g.d.3-4 and g.d.7-8. In situ localization of miR199a in rat uteri showed that miR199a was mainly localized in the stroma or decidua. The expression of miR199a was not significantly different in the uteri of pseudopregnant rats and evidently increased in the uteri of rats subjected to activation of delayed implantation and experimentally induced decidualization. Treatment with 17ß-estradiol or both 17ß-estradiol and progesterone significantly diminished miR199a levels. Gain of function of miR199a in endometrial stromal cells isolated from rat uteri inhibited cell proliferation and promoted cell apoptosis. Loss of function of miR199a displayed opposite roles on cell proliferation and apoptosis. Further investigation uncovered a significant inverse association between the expression of miR199a and growth factor receptor-bound protein 10 (Grb10), an imprinted gene, and miR199a could bind to the 3'UTR of Grb10 to inhibit Grb10 translation. In addition, in vivo analysis found that the immunostaining of GRB10 was attenuated in the stroma or decidua from g.d.4 to 6, contrary to the enhancement of miR199a. Collectively, upregulation of miR199a in rat uterus during the receptive phase is regulated by blastocyst activation and uterine decidualization. Enforced miR199a expression suppresses cell proliferation partially through targeting Grb10.

Harnessing the regenerative potential of interleukin11 to enhance heart repair.

Balancing between regenerative processes and fibrosis is crucial for heart repair, yet strategies regulating this balance remain a barrier to developing therapies. While Interleukin11 (IL11) is known as a fibrotic factor, its contribution to heart regeneration is poorly understood. We uncovered that il11a, an Il11 homolog in zebrafish, can trigger robust regenerative programs in zebrafish hearts, including cardiomyocytes proliferation and coronary expansion, even in the absence of injury. However, prolonged il11a induction in uninjured hearts causes persistent fibroblast emergence, resulting in fibrosis. While deciphering the regenerative and fibrotic effects of il11a, we found that il11-dependent fibrosis, but not regeneration, is mediated through ERK activity, suggesting to potentially uncouple il11a dual effects on regeneration and fibrosis. To harness the il11a's regenerative ability, we devised a combinatorial treatment through il11a induction with ERK inhibition. This approach enhances cardiomyocyte proliferation with mitigated fibrosis, achieving a balance between regenerative processes and fibrosis. Thus, we unveil the mechanistic insights into regenerative il11 roles, offering therapeutic avenues to foster cardiac repair without exacerbating fibrosis.

Cross-species single-cell comparison of systemic and cardiac inflammatory responses after cardiac injury.

The immune system coordinates the response to cardiac injury and is known to control regenerative and fibrotic scar outcomes in the heart and subsequent chronic low-grade inflammation associated with heart failure. Here we profiled the inflammatory response to heart injury using single cell transcriptomics to compare and contrast two experimental models with disparate outcomes. We used adult mice, which like humans lack the ability to fully recover and zebrafish which spontaneously regenerate after heart injury. The extracardiac reaction to cardiomyocyte necrosis was also interrogated to assess the specific peripheral tissue and immune cell reaction to chronic stress. Cardiac macrophages are known to play a critical role in determining tissue homeostasis by healing versus scarring. We identified distinct transcriptional clusters of monocytes/macrophages in each species and found analogous pairs in zebrafish and mice. However, the reaction to myocardial injury was largely disparate between mice and zebrafish. The dichotomous response to heart damage between the mammalian and zebrafish monocytes/macrophages may underlie the impaired regenerative process in mice, representing a future therapeutic target.

A beta cell subset with enhanced insulin secretion and glucose metabolism is reduced in type 2 diabetes.

The pancreatic islets are composed of discrete hormone-producing cells that orchestrate systemic glucose homeostasis. Here we identify subsets of beta cells using a single-cell transcriptomic approach. One subset of beta cells marked by high CD63 expression is enriched for the expression of mitochondrial metabolism genes and exhibits higher mitochondrial respiration compared with CD63lo beta cells. Human and murine pseudo-islets derived from CD63hi beta cells demonstrate enhanced glucose-stimulated insulin secretion compared with pseudo-islets from CD63lo beta cells. We show that CD63hi beta cells are diminished in mouse models of and in humans with type 2 diabetes. Finally, transplantation of pseudo-islets generated from CD63hi but not CD63lo beta cells into diabetic mice restores glucose homeostasis. These findings suggest that loss of a specific subset of beta cells may lead to diabetes. Strategies to reconstitute or maintain CD63hi beta cells may represent a potential anti-diabetic therapy.

miR-199a Is Upregulated in GDM Targeting the MeCP2-Trpc3 Pathway.

Gestational diabetes mellitus (GDM), the most common medical pregnancy complication, has become a growing problem. More and more studies have shown that microRNAs are closely related to metabolic processes. The purpose of this paper is to investigate the role of up-regulation of miR-199a-5p expression in GDM. We found that miR-199a-5p was significantly up-regulated in the placenta of GDM patients compared with normal pregnant women, and expressed in placental villi. miR-199a-5p can regulate the glucose pathway by inhibiting the expression of methyl CpG-binding protein 2 (MeCP2) and down-regulating canonical transient receptor potential 3 (Trpc3). This suggests that miR-199a-5p may regulate the glucose pathway by regulating methylation levels, leading to the occurrence of GDM.

BRPF1-KAT6A/KAT6B Complex: Molecular Structure, Biological Function and Human Disease.

The bromodomain and PHD finger-containing protein1 (BRPF1) is a member of family IV of the bromodomain-containing proteins that participate in the post-translational modification of histones. It functions in the form of a tetrameric complex with a monocytic leukemia zinc finger protein (MOZ or KAT6A), MOZ-related factor (MORF or KAT6B) or HAT bound to ORC1 (HBO1 or KAT7) and two small non-catalytic proteins, the inhibitor of growth 5 (ING5) or the paralog ING4 and MYST/Esa1-associated factor 6 (MEAF6). Mounting studies have demonstrated that all the four core subunits play crucial roles in different biological processes across diverse species, such as embryonic development, forebrain development, skeletal patterning and hematopoiesis. BRPF1, KAT6A and KAT6B mutations were identified as the cause of neurodevelopmental disorders, leukemia, medulloblastoma and other types of cancer, with germline mutations associated with neurodevelopmental disorders displaying intellectual disability, and somatic variants associated with leukemia, medulloblastoma and other cancers. In this paper, we depict the molecular structures and biological functions of the BRPF1-KAT6A/KAT6B complex, summarize the variants of the complex related to neurodevelopmental disorders and cancers and discuss future research directions and therapeutic potentials.