Abstract
Abdominal aortic aneurysm (AAA) is a life-threatening vascular disease with no effective pharmacological interventions. While single-cell transcriptomics has advanced our understanding of AAA, it lacks spatial context. Here, we employed Seq-Scope, an ultra-high-resolution spatial transcriptomic technology, to decipher the spatial landscape of angiotensin II–induced AAA in Apoe–/– mice. Our analysis revealed the heterogeneity of macrophages, fibroblasts, and smooth muscle cells (SMCs), with specific responses in different layers of the AAA tissue. SMCs in the inner layers showed associations with Mgp-expressing fibroblasts and GPNMB-expressing macrophages, whereas the outer layers had different dominant cell types. Notably, GPNMB-expressing macrophages were concentrated near SMCs in regions of severe elastic lamina damage. Immunofluorescent staining confirmed their colocalization, and scRNA-seq reanalysis independently validated the presence of GPNMB-high macrophages in AAA tissues, highlighting their involvement in inflammation and tissue remodeling. Moreover, we discovered that macrophage-derived soluble GPNMB induces SMC phenotypic switching, reducing contractile markers while increasing cytokines and metalloproteinases. This effect was partly mediated by CD44 signaling. These findings suggest that GPNMB-high macrophages contribute to AAA development by driving SMC dysfunction. This study highlights the importance of high-resolution spatial transcriptomics in complementing single-cell transcriptomics, offering valuable insights into molecular and cellular responses in the AAA microenvironment.
Authors
Guizhen Zhao, Chun-Seok Cho, Hongyu Liu, Yongha Hwang, Yichen Si, Myungjin Kim, Yongjie Deng, Yang Zhao, Chao Xue, Yanhong Guo, Lin Chang, Dogukan Mizrak, Bo Yang, Hyun Min Kang, Jifeng Zhang, Jun Hee Lee, Y. Eugene Chen
Abstract
Authors
Joshua A. Keefe, Jose Alberto Navarro-Garcia, Shuai Zhao, Mihail G. Chelu, Xander H.T. Wehrens
Citation Information: JCI Insight. 2025;10(15):e187942. https://doi.org/10.1172/jci.insight.187942.
Abstract
Hypertrophic cardiomyopathy (HCM) is a hereditary heart condition characterized by either preserved or reduced ejection fraction without any underlying secondary causes. The primary cause of HCM is sarcomeric gene mutations, which account for only 40%–50% of the total cases. Here, we identified a pathogenic missense variant in tubulin tyrosine ligase (TTL p.G219S) in a patient with HCM. We used clinical, genetics, computational, and protein biochemistry approaches, as well as patient-specific and CRISPR gene-edited induced pluripotent stem cell–derived cardiomyocytes (iPSC-CMs), to demonstrate that the TTL pathogenic variant results in a reduced enzymatic activity and the accumulation of detyrosinated tubulin leading to the disruption of redox signaling, ultimately leading to HCM. Our findings highlight — for the first time to our knowledge — the crucial roles of the TTL variant in cardiac remodeling resulting in disease.
Authors
Pratul Kumar Jain, Susobhan Mahanty, Harshil Chittora, Veronique Henriot, Carsten Janke, Minhajuddin Sirajuddin, Perundurai S. Dhandapany
Abstract
Pathological cardiac remodeling is associated with the reactivation of fetal genes, yet the extent of the heart’s fetal gene program and its impact on proteome compositions remain incompletely understood. Here, using a new proteome-wide protein ratio quantification strategy with mass spectrometry, we identify pervasive isoform usage shifts in fetal and postnatal mouse hearts, involving 145 pairs of highly homologous paralogs and alternative splicing-derived isoform proteins. Proteome-wide ratio comparisons readily rediscover hallmark fetal gene signatures in muscle contraction and glucose metabolism pathways, while revealing novel isoform usage in mitochondrial and gene expression proteins, including PPA1/PPA2, ANT1/ANT2, and PCBP1/PCBP2 switches. Paralogs with differential fetal usage tend to be evolutionarily recent, consistent with functional diversification. Alternative splicing adds another rich source of fetal isoform usage differences, involving PKM M1/M2, GLS-1 KGA/GAC, PDLIM5 long/short, and other spliceoforms. When comparing absolute protein proportions, we observe a partial reversion toward fetal gene usage in pathological hearts. In summary, we present a ratiometric catalog of paralogs and spliceoform pairs in the cardiac fetal gene program. More generally, the results demonstrate the potential of applying the proteome-wide ratio test concept to discover new regulatory modalities beyond differential gene expression.
Authors
Yu Han, Shaonil Binti, Sara A. Wennersten, Boomathi Pandi, Dominic C.M. Ng, Edward Lau, Maggie P.Y. Lam
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.190918.
Abstract
Biallelic variants in SCN1B, encoding the voltage-gated sodium channel β1/β1B subunits, are linked to DEE52, a developmental and epileptic encephalopathy with a high risk of Sudden Unexpected Death in Epilepsy (SUDEP). DEE52 patients present clinically with Dravet syndrome or the more severe early infantile DEE. SCN1B is expressed in brain and heart in humans and in mice. Thus, we have proposed that, in addition to generalized seizures, cardiac arrhythmia may play a role in SUDEP. Mice with homozygous expression of the DEE52 variant Scn1b-c.265C>T, predicting p.R89C, have spontaneous and hyperthermia-induced generalized seizures and SUDEP. Here we conducted cardiac characterization of Scn1b-c.265C>T mice and studied induced pluripotent stem cell cardiomyocytes (iPSC-CMs) derived from two SCN1B-c.265C>T DEE52 patients. Scn1bC89/C89 mouse CMs showed increased transient outward potassium current (Ito) density and heart sections revealed ventricular fibrosis. Scn1bC89/C89 mice were susceptible to pacing-induced cardiac arrhythmias. Patient-derived iPSC-CMs with biallelic SCN1B-c.265C>T variant expression showed increased sodium current (INa), late INaL, and Ito current densities. We conclude that, while mouse and human cardiac AP waveforms have critical differences, increased Ito is common to both models of DEE52. Overall, our data suggest that electrical and structural substrates may lead to arrhythmias and contribute to SUDEP in DEE52.
Authors
Roberto Ramos-Mondragon, Shuyun Wang, Nnamdi Edokobi, Qinghua Liu, Xiaotan Qiao, Maya Shih, Louis T. Dang, Yao-Chang Tsan, Katalin Štěrbová, Adam S. Helms, Sarah Weckhuysen, Luis F. Lopez-Santiago, Jack M. Parent, Lori L. Isom
Abstract
Heterozygosity for missense mutations in one of 3 seemingly redundant calmodulin (CALM)-encoding genes can cause life-threatening arrhythmias, suggesting that small fractions of mutant CALM protein suffice to cause a severe phenotype. However, the exact molar ratios of wildtype to mutant CALM protein in calmodulinopathy hearts remain unknown. The aim of the present study was to quantitate mutant versus wildtype CALM transcript and protein levels in hearts of knock-in mice harboring the p.N98S mutation in the Calm1 gene. We found that the transcripts from the mutant Calm1 allele were the least abundantly expressed Calm transcripts in both hetero- and homozygous mutant hearts, while mutant hearts accumulate high levels of N98S-CALM protein in a Calm1N98S allele dosage-dependent manner, exceeding those of wildtype CALM protein. We further show that the severity of the electrophysiological phenotype incrementally increases with the graded increase in the mutant-to-wildtype CALM protein expression ratio seen in homozygous versus heterozygous mutant mice. We finally show a decrease in N98S-CALM protein degradation, suggesting that mutant CALM stabilization contributed to its enrichment in the heart. Our results support what we believe to be a novel mechanism by which a mutation in a single Calm gene can give rise to a severe phenotype.
Authors
Wen-Chin Tsai, Chiu-Fen Yang, Shu-Yu Lin, Suh-Yuen Liang, Wei-Chung Tsai, Shuai Guo, Xiaochun Li, Susan Ofner, Kai-Chien Yang, Tzu-Ching Meng, Peng-Sheng Chen, Michael Rubart
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.192283.
Abstract
Hereditary cardiomyopathies are the prototypic forms of heart failure and major causes of sudden cardiac death. The genome in cardiomyopathies is exposed to internal stressors, which damage the DNA and activate the DNA damage response (DDR) pathways. We set to determine whether the DDR pathways were activated and pathogenic in an established mouse model of desmoplakin (DSP)-cardiomyopathy generated upon deletion of the Dsp gene in cardiac myocytes (Myh6-McmTam:DspF/F). The mice exhibited premature death, cardiac dysfunction, myocardial cell death, fibrosis, and increased expression levels of the pro-inflammatory cytokines, consistent with the phenotype of human DSP-cardiomyopathy. Cytosolic nuclear self-DNA (nDNA) and mitochondrial DNA (mtDNA) were increased in cardiac myocyte cytosol in the Myh6-McmTam:DspF/F mice. Likewise, the DDR pathway proteins, including the cyclic GMP-AMP synthase (CGAS), stimulator of interferon response 1 (STING1) were upregulated as were the transcript levels of interferon response factor 3 (IRF3) and the nuclear factor κB (NFκB) target genes. Deletion of the Mb21d1 gene encoding CGAS in the Myh6-McmTam:DspF/F mice prolonged survival, improved cardiac function, attenuated fibrosis, and reduced cell death. Thus, cytosolic nDNA and mtDNA are increased and the DDR pathways are activated and pathogenic in a mouse model of DSP-cardiomyopathy, whereas genetic blockade of CGAS is salubrious.
Authors
Weiyue Wang, Benjamin Cathcart, Quoc D. Nguyen, Loi Q. Lao, Amelia Bryans, Sara E. Coleman, Leila Rouhi, Priyatansh Gurha, Ali J. Marian
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.189008.
Abstract
BACKGROUND. Thymic involution with age leads to reduced T cell output and impaired adaptive immunity. However, the extent to which thymic activity persists later in life and how this contributes to immunological ageing remains unclear. This study aimed to assess the presence and function of thymic tissue in older adults and identify factors influencing residual thymopoiesis. METHODS. Patients aged ≥ 50 undergoing cardiothoracic surgery were recruited. Thymic structures within mediastinal adipose tissue were evaluated using histology, immunofluorescence, flow cytometry, TCR sequencing, and RNA sequencing. Recent thymic emigrants (RTEs) were quantified in peripheral blood and correlated with transcriptomic, epigenetic, and TCR repertoire data. Primary outcomes included thymic tissue identification, RTE frequency, and immune correlates. RESULTS. Functional thymic tissue was identified in mediastinal adipose tissue of older individuals. The frequency of CD31+CD4+ T cells (RTEs) positively correlated with the presence of thymic tissue. Thymic output showed substantial heterogeneity and was influenced by sex and smoking history. Thymic activity was associated with increased TCR repertoire diversity, improved immune protection to infections, and reduced epigenetic ageing. Detailed profiling uncovered functional and phenotypic heterogeneity within naïve CD4+ T cell subsets shaped by thymic activity. CONCLUSION. This study demonstrates that thymic function can persist into later life and is modulated by factors such as sex and smoking. These findings suggest that thymic activity during ageing is heterogenous and influenced by more than chronological age alone, with potential implications for immune competence in older adults.
Authors
Balraj Sandhar, Vishal Vyas, Daniel Harding, Roberta Ragazzini, Paola Bonfanti, Federica M. Marelli-Berg, Christopher G. Bell, Benny M. Chain, M. Paula Longhi
Citation Information: JCI Insight. 2025;10(9):e189323. https://doi.org/10.1172/jci.insight.189323.
Abstract
Patients with viral myocarditis (VMC) exhibit evident autonomic nervous system imbalance, and adverse cardiac remodeling is involved in impaired cholinergic function. The α7 nicotinic acetylcholine receptor (α7nAChR), which is a neurotransmitter receptor, exerts immunoregulatory effects. Recent advances have illuminated the evolution and functions of peripheral and cardiac B cells in heart disease. However, the role of α7nAChR expressed by B cells in the progression of VMC has not been established. We revealed the neuroimmune communication landscape in the heart and found that the phenotypes of cardiac and splenic B cells and their α7nAChR expression changed dynamically during the progression of VMC to dilated cardiomyopathy. α7nAChR on B cells serves as a negative regulator by inhibiting their proinflammatory functions and signaling pathways. B cell–specific α7nAChR deficiency exacerbated myocardial inflammation, fibrosis, and cardiac dysfunction. However, these effects were abrogated in non-B cells from mice with IL-17A knockdown. Enhanced degradation of acetylcholine leads to an imbalance in cholinergic signaling, resulting in impaired neurotransmission. The acetylcholinesterase inhibitor pyridostigmine bromide could improve cardiac remodeling and prevent the progression of VMC to the chronic phase, which was partly dependent on the α7nAChR on B cells. Our findings provide notable insights into cardiac-neural-immune communication during myocardial injury.
Authors
Jing Lu, Keren Chen, Zhihong Cen, Yanlan Huang, Yong Li, LiLi Chen, Weifeng Wu
Citation Information: JCI Insight. 2025. https://doi.org/10.1172/jci.insight.188414.
Abstract
Regulation of organismal homeostasis in response to nutrient availability is a vital physiological process that involves inter-organ communication. The role of the heart in controlling systemic metabolic health is not clear. Adopting a mouse model of diet-induced obesity, we found that the landscape of N6-methyladenosine (m6A) on cardiac mRNA is altered following high fat/high carbohydrate feeding (western diet). m6A is a critical post-transcriptional regulator of gene expression, the formation of which is catalyzed by methyltransferase-like 3 (METTL3). Through parallel unbiased approaches of nanopore sequencing, mass spectrometry, and protein array, we found regulation of circulating factors under the control of METTL3. Mice with cardiomyocyte-specific deletion of METTL3 show a systemic inability to respond to nutritional challenge, thereby mitigating the detrimental effects of western diet. Conversely, increasing cardiac METTL3 level exacerbates diet-induced body weight gain, adiposity, and glucose intolerance. Our findings position the heart at the center of systemic metabolism regulation and highlight an m6A-dependent pathway to be exploited for the battle against obesity.
Authors
Charles Rabolli, Jacob Z. Longenecker, Isabel S. Naarmann-de Vries, Joan Serrano, Jennifer M. Petrosino, George A. Kyriazis, Christoph Dieterich, Federica Accornero
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