Biology subjects

Weinheimer, C. J.

Publications and source records attributed to Weinheimer, C. J..

9 recordsLinked to original sources

bioRxiv2026

Collateral Immune Cell Signaling Compromises the Efficacy of T-cell Engaging Therapies for Cardiac Fibrosis

Cardiac fibrosis is causally linked to heart failure progression and survival. Currently, there are no approved treatments that directly target cardiac fibrosis. Recent studies have identified a subset of activated cardiac fibroblasts distinct from myofibroblasts that are marked by fibroblast activation protein (FAP) expression, emerge in the injured and diseased heart through inflammatory signaling, and contribute to fibrosis. Using a genetic mouse model, we demonstrate the potential benefits of FAP+ fibroblast depletion following myocardial infarction. Unexpectedly, while FAP targeted bispecific T-cell engaging antibodies (BiTE(R) molecules) effectively eliminate FAP+ fibroblasts from the heart, they surprisingly lead to accelerated deterioration of cardiac function, enhanced remodeling, and increased scar size. FAP BiTE(R) molecules elicit a robust cytokine response within the heart with prominent activation of interferon gamma (IFNg) and CD40 ligand pathways. Target cell killing was independent of IFNg; and CD40L signaling and blockade of these pathways was sufficient to unmask the protective therapeutic effects of FAP+ fibroblast depletion. Mechanistically, we reveal that IFNg; signaling to fibroblasts drives the differentiation of an independent lineage of activated fibroblasts not typically found in the infarcted heart, which are responsible for the harmful effects of FAP BiTE(R) molecules. Collectively, these findings highlight a previously unrecognized cardiac liability of BiTE(R) molecules and inform the design of the next generation of therapeutics.

immunology↗

bioRxiv2025

Targeting RUNX1 in Macrophages Facilitates Cardiac Recovery

Despite advances in disease treatment, our understanding of how damaged organs recover and the mechanisms governing this process remain poorly defined. Here, we mapped the transcriptional and regulatory landscape of human cardiac recovery using single cell multiomics. Macrophages emerged as the most reprogrammed cell type. Deep learning identified the transcription factor RUNX1 as a key regulator of this process. Macrophage-specific Runx1 deletion recapitulated the human cardiac recovery phenotype in a chronic heart failure model. Runx1 deletion reprogrammed macrophages to a reparative phenotype, reduced fibrosis, and promoted cardiomyocyte adaptation. RUNX1 chromatin profiling revealed a conserved regulon that diminished during recovery. Mechanistically, the epigenetic reader BRD4 controlled Runx1 expression in macrophages. Chromatin activity mapping, combined with CRISPR perturbations, identified the precise regulatory element governing Runx1 expression. Therapeutically, small molecule Runx1 inhibition was sufficient to promote cardiac recovery. Our findings uncover a druggable RUNX1 epigenetic mechanism that orchestrates recovery of heart function.

immunology↗

bioRxiv2024

Phosphorylation of CRYAB Induces a Condensatopathy to Worsen Post-Myocardial Infarction Left Ventricular Remodeling.

Protein aggregates are emerging therapeutic targets in rare monogenic causes of cardiomyopathy and amyloid heart disease, but their role in more prevalent heart failure syndromes remains mechanistically unexamined. We observed mis-localization of desmin and sarcomeric proteins to aggregates in human myocardium with ischemic cardiomyopathy and in mouse hearts with post-myocardial infarction ventricular remodeling, mimicking findings of autosomal-dominant cardiomyopathy induced by R120G mutation in the cognate chaperone protein, CRYAB. In both syndromes, we demonstrate increased partitioning of CRYAB phosphorylated on serine-59 to NP40-insoluble aggregate-rich biochemical fraction. While CRYAB undergoes phase separation to form condensates, the phospho-mimetic mutation of serine-59 to aspartate (S59D) in CRYAB mimics R120G-CRYAB mutants with reduced condensate fluidity, formation of protein aggregates and increased cell death. Conversely, changing serine to alanine (phosphorylation-deficient mutation) at position 59 (S59A) restored condensate fluidity, and reduced both R120G-CRYAB aggregates and cell death. In mice, S59D CRYAB knock-in was sufficient to induce desmin mis-localization and myocardial protein aggregates, while S59A CRYAB knock-in rescued left ventricular systolic dysfunction post-myocardial infarction and preserved desmin localization with reduced myocardial protein aggregates. 25-Hydroxycholesterol attenuated CRYAB serine-59 phosphorylation and rescued post-myocardial infarction adverse remodeling. Thus, targeting CRYAB phosphorylation-induced condensatopathy is an attractive strategy to counter ischemic cardiomyopathy.

cell biology↗

bioRxiv2024

Ketone Body Metabolism is Not Required for Improvement of Heart Failure by Ketogenic Diet in Mice

Failing hearts increasingly metabolize ketone bodies, and enhancing ketosis improves heart failure (HF) remodeling. Circulating ketones are elevated by fasting/starvation, which is mimicked with a high-fat, low-carbohydrate "ketogenic diet" (KD). While speculated that KD improves HF through increased ketone oxidation, some evidence suggests KD paradoxically downregulates cardiac ketone oxidation despite increased ketone delivery. We sought to clarify the significance of cardiac ketone metabolism during KD in HF. Mice were subjected to transverse aortic constriction with apical myocardial infarction (TAC-MI) and fed either low-fat (LF) control or KD. Cardiac-specific mitochondrial pyruvate carrier 2 (csMPC2-/-) mice were used as a second model of heart failure. In both mice, feeding a KD improved HF, determined by echocardiography, heart weights, and gene expression analyses. Although KD increases plasma ketone bodies, gene expression for ketone metabolic genes is decreased in the hearts of KD-fed mice. Cardiac-specific {beta}-hydroxybutyrate dehydrogenase 1 (csBDH1-/-), the first enzyme in ketone catabolism, mice were also studied and crossed with the csMPC2-/-mice to create double knockout (DKO) mice. These mice were aged to 16 weeks and switched to LF or KD, and KD was able to completely normalize the hearts of both csMPC2-/- and DKO mice, suggesting that ketone metabolism is unnecessary for improving heart failure with ketogenic diet. These studies were then repeated, and mice injected with U-13C-{beta}-hydroxybutyrate to evaluate ketone metabolism. KD feeding significantly decreased the enrichment of the TCA cycle from ketone body carbons, as did the BDH1-deletion in DKO mice. Gene expression and respirometry suggests that KD instead increases cardiac fat oxidation. In conclusion, these results suggest that ketogenic diet decreases cardiac ketone metabolism and does not require ketone metabolism to improve heart failure.

physiology↗

bioRxiv2023

Genetic Mapping of Monocyte Fate Decisions Following Myocardial Infarction

Inflammation contributes to the pathogenesis of myocardial infarction and heart failure and represents a viable therapeutic target. Monocytes and their progeny are highly abundant and display incredible functional diversity, serving as key determinants of myocardial inflammation and tissue repair. Much remains to be learned regarding mechanisms and signaling events that instruct monocyte fate decisions. We devised a genetic lineage tracing strategy using Ccr2crERT2Rosa26LSL-tdTomato mice in combination with single cell RNA-sequencing to map the differentiation trajectories of monocytes that infiltrate the heart after reperfused myocardial infarction. Monocytes are recruited to the heart early after injury and give rise to transcriptionally distinct and spatially restricted macrophage and dendritic cell-like subsets that are specified prior to extravasation and chronically persist within the myocardium. Pseudotime analysis predicted two differentiation trajectories of monocyte-derived macrophages that are partitioned into the border and infarct zones, respectively. Among these trajectories, we show that macrophages expressing a type I IFN responsive signature are an intermediate population that gives rise to MHC-IIhi macrophages, are localized within the border zone, and promote myocardial protection. Collectively, these data uncover new complexities of monocyte differentiation in the infarcted heart and suggest that modulating monocyte fate decisions may have clinical implications.

immunology↗

bioRxiv2022

Hypoxia Sensing in Resident Cardiac Macrophages Regulates Monocyte-Derived Macrophage Fate Specification following Myocardial Infarction

Myocardial infarction initiates cardiac remodeling and is central to heart failure pathogenesis. Following myocardial ischemia reperfusion injury, monocytes enter the heart and differentiate into diverse subpopulations of macrophages. The mechanisms and dynamics of monocyte differentiation within this context are unknown. We investigated the role of macrophage hypoxia sensing on monocyte differentiation following reperfused myocardial infarction. We show that deletion of Hif1, a hypoxia response transcription factor, in resident cardiac macrophages led to increased remodeling and overrepresentation of a macrophage subset marked by arginase 1 (Arg1) expression. Arg1+ macrophages displayed an inflammatory gene signature and were predicted to represent an intermediate state within the monocyte differentiation cascade. Lineage tracing of Arg1+ macrophages revealed the existence of a monocyte differentiation trajectory consisting of multiple transcriptionally distinct macrophage states. We further showed that deletion of Hif1 in resident cardiac macrophages resulted in arrested progression through this trajectory and accumulation of an inflammatory intermediate state marked by persistent Arg1 expression. Collectively, our findings unveil distinct trajectories of monocyte differentiation and identify hypoxia sensing as an important determinant of monocyte differentiation following myocardial infarction.

immunology↗

bioRxiv2022

Dapagliflozin improves endothelial integrity and hemodynamics in endotoxin treated mice through an apolipoprotein M dependent pathway

RationaleSodium-glucose co-transporter inhibitors (SGLT2i) are under active clinical investigation in patients with acute inflammatory conditions, based on their clinical cardio-and nephroprotective effects, and a pre-clinical study that demonstrated SGLT2i improve renal outcomes and survival in a lipopolysaccharide (LPS) model. However, a unified mechanism that explains how SGLT2i could prevent hemodynamic consequences of inflammatory conditions has not been described. Apolipoprotein M (ApoM) is inversely associated with mortality in inflammatory conditions and improves cardiac function in endotoxin-treated mice via sphingosine-1-phosphate (S1P) signaling. ObjectiveTest the hypothesis that pre-treatment with SGLT2i dapagliflozin (Dapa) improves hemodynamics in endotoxin-treated mice via the ApoM/S1P pathway. Methods and ResultsMice with diet-induced obesity were gavaged with vehicle or Dapa for 4 days prior to LPS (10 mg/kg, IP). We found that mice receiving Dapa restored circulating ApoM levels, likely by increasing expression of the multi-ligand protein receptor megalin in the proximal tubules. Dapa attenuated LPS-induced reductions in cardiac dysfunction including reductions in ejection fraction, cardiac index, and coronary sinus area as well as vascular permeability as ascertained by intravital microscopy. Using both ApoM transgenic and knockout mice and S1P receptor inhibitors, we show that the ApoM/S1P pathway is important for the beneficial effects of Dapa in the LPS model. ConclusionsIn the setting of acute inflammation, our data suggest that SGLT2i maintains levels of megalin, leading to preservation of ApoM, which in turn promotes endothelial barrier integrity and improves hemodynamics. Our studies suggest a novel mechanism by which SGLT2i can preserve intravascular volume in the acute inflammatory setting.

physiology↗

bioRxiv2021

Resident Cardiac Macrophages Mediate Adaptive Myocardial Remodeling

Cardiac macrophages represent a heterogeneous cell population with distinct origins, dynamics, and functions. Recent studies have revealed that C-C Chemokine Receptor 2 positive (CCR2+) macrophages derived from infiltrating monocytes regulate myocardial inflammation and heart failure pathogenesis. Comparatively little is known about the functions of tissue resident (CCR2-) macrophages. Herein, we identify an essential role for CCR2- macrophages in the chronically failing heart. Depletion of CCR2- macrophages in mice with dilated cardiomyopathy accelerated mortality and impaired ventricular remodeling and coronary angiogenesis, adaptive changes necessary to maintain cardiac output in the setting of reduced cardiac contractility. Mechanistically, CCR2- macrophages interacted with neighboring cardiomyocytes via focal adhesion complexes and were activated in response to mechanical stretch through a transient receptor potential vanilloid 4 (TRPV4) dependent pathway that controlled growth factor expression. These findings establish a role for tissue resident macrophages in adaptive cardiac remodeling and introduce a new mechanism of cardiac macrophage activation.

immunology↗

bioRxiv2020

Ketogenic Diet Prevents Heart Failure from Defective Mitochondrial Pyruvate Metabolism

The myocardium is metabolically flexible and can use fatty acids, glucose, lactate/pyruvate, ketones, or amino acids to fuel mechanical work. However, impaired metabolic flexibility is associated with cardiac dysfunction in conditions including diabetes and heart failure. The mitochondrial pyruvate carrier (MPC) is required for pyruvate metabolism and is composed of a hetero-oligomer of two proteins known as MPC1 and MPC2. Interestingly, MPC1 and MPC2 expression is downregulated in failing human hearts and in a mouse model of heart failure. Mice with cardiac-specific deletion of MPC2 (CS-MPC2-/-) exhibited loss of both MPC2 and MPC1 proteins and reduced pyruvate-stimulated mitochondrial respiration. CS-MPC2-/- mice exhibited normal cardiac size and function at 6-weeks old, but progressively developed cardiac dilation and contractile dysfunction thereafter. Feeding CS-MPC2-/- mice a ketogenic diet (KD) completely prevented or reversed the cardiac remodeling and dysfunction. Other diets with higher fat content and enough carbohydrate to limit ketosis also improved heart failure in CS-MPC2-/- mice, but direct ketone body provisioning provided only minor improvements in cardiac remodeling. Finally, KD was also able to prevent further remodeling in an ischemic, pressure-overload mouse model of heart failure. In conclusion, loss of mitochondrial pyruvate utilization leads to dilated cardiomyopathy that can be corrected by a ketogenic diet.

physiology↗