Biology subjects

Cannon, E. N.

Publications and source records attributed to Cannon, E. N..

3 recordsLinked to original sources

bioRxiv2026

NETosis and Myeloperoxidase Promotes Inflammation and Cardiac Remodeling in Arrhythmogenic Cardiomyopathy

BackgroundArrhythmogenic cardiomyopathy (ACM) is a heritable nonischemic cardiomyopathy and a leading cause of sudden cardiac death. Although inflammation is a pathological hallmark of ACM, the contribution of peptidylarginine deiminase 4 (PAD4)-dependent neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) to disease progression remains poorly defined. MethodsTo define the role of PAD4-dependent NETosis and MPO signaling in ACM disease progression homozygous desmoglein-2 mutant (Dsg2mut/mut) mice were utilized. We employed genetic and pharmacological approaches to determine the efficacy of targeting PAD4 and MPO on cardiac function, arrhythmogenic burden, myocardial fibrosis, inflammatory signaling, and gap junction integrity. Cardiac phenotyping included echocardiography, electrocardiography, histology, inflammatory profiling, and biochemical assays. ResultsMarkers of PAD4-dependent NETosis were elevated in Dsg2mut/mut hearts as early as 4 weeks of age, prior to cardiac dysfunction. Genetic deletion of Pad4 significantly preserved left ventricular function, reduced ectopics, attenuated myocardial fibrosis, and suppressed proinflammatory and profibrotic cytokines. MPO levels were increased in Dsg2mut/mut hearts, and genetic ablation of Mpo preserved cardiac function, reduced arrhythmic burden, prevented myocardial fibrosis, and restored connexin-43 phosphorylation and localization. Furthermore, pharmacological MPO-inhibition improved cardiac function, reduced arrhythmias, and attenuated inflammatory signaling, though myocardial fibrosis was not fully prevented. Notably, hearts from patients with ACM demonstrated increased MPO signal in both cardiomyocytes and non-cardiomyocyte populations compared with donor controls. ConclusionsPAD4-dependent NETosis and MPO signaling are key drivers of inflammation, fibrosis, and arrhythmogenesis in early disease onset in ACM. Targeting neutrophil-mediated pathways represents a promising therapeutic strategy to mitigate disease progression in ACM. Clinical PerspectiveO_ST_ABSWhat Is New?C_ST_ABSO_LIPAD4-dependent NET formation is activated early in ACM and directly contributes to myocardial inflammation, fibrosis, arrhythmias, and cardiac dysfunction. C_LIO_LIGenetic ablation of Pad4 or Mpo preserves cardiac function, reduces arrhythmogenic burden, and attenuates proinflammatory and profibrotic signaling in a Dsg2 mutant model of ACM. C_LIO_LIPharmacological inhibition of MPO improves cardiac function and electrical stability, identifying neutrophil-derived pathways as modifiable drivers of disease. C_LI What Are the Clinical Implications?O_LINeutrophil-mediated inflammation represents a clinically relevant mechanism in ACM that may be targeted without global immunosuppression. C_LIO_LIMPO inhibition may offer a novel disease-modifying strategy to reduce arrhythmias and preserve cardiac function in patients with ACM. C_LIO_LINeutrophil- and NET-associated biomarkers may improve early risk stratification and therapeutic decision-making in genetically susceptible individuals. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/718596v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@14efa56org.highwire.dtl.DTLVardef@152cfaorg.highwire.dtl.DTLVardef@3bfe43org.highwire.dtl.DTLVardef@b20cef_HPS_FORMAT_FIGEXP M_FIG C_FIG (A) Signaling pathway for PAD4-dependent NETosis. (B) Illustration of neutrophil undergoing NETosis resulting in the release of MPO and DNA histone complexes. (C) Effects of MPO release on cardiac tissue of ACM mice

pathology↗

bioRxiv2024

Interleukin-1β Drives Disease Progression in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy (ACM) is a genetic form of heart failure that affects 1 in 5000 people globally and is caused by mutations in cardiac desmosomal proteins including PKP2, DSP, and DSG2. Individuals with ACM suffer from ventricular arrhythmias, sudden cardiac death, and heart failure. There are few effective treatments and heart transplantation remains the best option for many affected individuals. Here we performed single nucleus RNA sequencing (snRNAseq) and spatial transcriptomics on myocardial samples from patients with ACM and control donors. We identified disease-associated spatial niches characterized by co-existence of fibrotic and inflammatory cell types and failing cardiac myocytes. The inflammatory-fibrotic niche co-localized to areas of cardiac myocyte loss and was comprised of FAP (fibroblast activation protein) and POSTN (periostin) expressing fibroblasts and macrophages expressing NLRP3 (NLR family pyrin domain containing 3) and NFB activated genes. Using homozygous Desmoglein-2 mutant (Dsg2mut/mut) mice, we identified analogous populations of Postn expressing fibroblasts and inflammatory macrophage populations that co-localized within diseased areas. Detailed single cell RNA sequencing analysis of inflammatory macrophage subsets that were increased in ACM samples revealed high levels of interleukin-1{beta} (Il1b) expression. To delineate the possible benefit of targeting IL-1{beta} in ACM, we treated Dsg2mut/mut mice with an anti-IL-1{beta} neutralizing antibody and observed attenuated fibrosis, reduced levels of inflammatory cytokines and chemokines, preserved cardiac function, and diminished conduction slowing and automaticity, key mechanisms of arrhythmogenesis. These results suggest that currently approved therapeutics that target IL-1{beta} or IL-1 signaling may improve outcomes for patients with ACM.

immunology↗

bioRxiv2023

Mechanisms of Innate Immune Injury in Arrhythmogenic Cardiomyopathy

Inhibition of nuclear factor kappa-B (NF{kappa}B) signaling prevents disease in Dsg2mut/mut mice, a model of arrhythmogenic cardiomyopathy (ACM). Moreover, NF{kappa}B is activated in ACM patient-derived iPSC-cardiac myocytes under basal conditions in vitro. Here, we used genetic approaches and sequencing studies to define the relative pathogenic roles of immune signaling in cardiac myocytes vs. inflammatory cells in Dsg2mut/mutmice. We found that NF{kappa}B signaling in cardiac myocytes drives myocardial injury, contractile dysfunction, and arrhythmias in Dsg2mut/mut mice. It does this by mobilizing cells expressing C-C motif chemokine receptor-2 (CCR2+ cells) to the heart, where they mediate myocardial injury and arrhythmias. Contractile dysfunction in Dsg2mut/mut mice is caused both by loss of heart muscle and negative inotropic effects of inflammation in viable muscle. Single nucleus RNA sequencing and cellular indexing of transcriptomes and epitomes (CITE-seq) studies revealed marked pro-inflammatory changes in gene expression and the cellular landscape in hearts of Dsg2mut/mut mice involving cardiac myocytes, fibroblasts and CCR2+ cells. Changes in gene expression in cardiac myocytes and fibroblasts in Dsg2mut/mutmice were modulated by actions of CCR2+ cells. These results highlight complex mechanisms of immune injury and regulatory crosstalk between cardiac myocytes, inflammatory cells, and fibroblasts in the pathogenesis of ACM. BRIEF SUMMARYWe have uncovered a therapeutically targetable innate immune mechanism regulating myocardial injury and cardiac function in a clinically relevant mouse model of Arrhythmogenic Cardiomyopathy (ACM).

immunology↗