Biology subjects

Leipold, A. M.

Publications and source records attributed to Leipold, A. M..

4 recordsLinked to original sources

bioRxiv2026

Neutrophil terminal programming in the ischemic heart drives fibrosis after myocardial infarction

Following myocardial infarction (MI), the heart undergoes massive neutrophil infiltration characterized by the emergence of distinct subsets, notably a SiglecF+ population that accumulates according to specific temporal dynamics. The mechanisms governing cardiac neutrophil heterogeneity and the subsequent functional impact of this diversity on tissue repair following myocardial infarction remain to be elucidated. Using single-cell RNA-sequencing of neutrophils in the heart and peripheral organs of infarcted mice, we here show that while acquisition of the SiglecF+ state only fully occurs in the ischemic heart tissue, MI primes neutrophils in the periphery to acquire Siglecf and to upregulate receptors for TGF{beta} and GM-CSF that drive acquisition of the SiglecF+ state. Ly6G targeting in vivo shifted cardiac neutrophils towards the SiglecF+ state at day 3 post-MI, induced the emergence of reprogrammed SiglecF+Ly6Glo and Retnlghi neutrophil states at day 5, and was associated with increased fibrosis of the infarct border zone. Mechanistically, Ly6G targeting reshaped the cardiac immune landscape with increased recruitment of pro-fibrotic {gamma}{delta} T cells and monocytes, and SiglecF+ neutrophils exerted direct pro-fibrotic effects on fibroblasts in a co-culture system. Altogether, our results indicate that peripheral neutrophil priming combined with their terminal programming towards a SiglecF+ state in the ischemic heart drives cardiac fibrosis after MI.

physiology↗

bioRxiv2025

Murine CMV Infection Unmasks Macrophage-Driven Inflammatory Cardiomyopathy in Pkp2, but not in Ttn Mutant Mice

2.BackgroundGenetic cardiomyopathies display variable penetrance and phenotypic expression, highlighting the influence of environmental modulators. Myocarditis, commonly triggered by cardiotropic viruses, overlaps clinically with genetic cardiomyopathies. Consequently, these infections are implicated as secondary factors that accelerate disease onset and progression, yet their precise impact in specific genetic settings remains unexplored. MethodsTo interrogate this, genetic mouse models heterozygous for a mutant allele of desmosomal plakophilin-2 (Pkp2+/-) or sarcomeric titin (Ttn+/-), genes frequently linked to acute myocarditis, were challenged with murine cytomegalovirus (MCMV) to determine how latent infection influences myocardial inflammation, tissue remodeling, and cardiac performance. Integrated experimental approaches, including echocardiography, histology, flow cytometry, single-cell RNA sequencing, as well as cytokine and kinome analyses, defined immune and signaling responses in infected versus non-infected hearts. ResultsAcute, MCMV-induced viral myocarditis and subsequent latent MCMV infection unmasked early disease onset in Pkp2+/- animals, leading to progressive systolic impairment, whereas in Ttn+/- mice cardiac structure and function remained preserved throughout infection. Cardiac immune profiling uncovered infection- and genotype-specific divergence: both genetic models showed a stable myocardial effector-memory CD8+ T-cell response to MCMV, but only Pkp2+/- hearts recruited additional Ly6C+ CCR2+ monocytes and macrophages with distinct inflammatory signatures. In the absence of infection, Pkp2 insufficiency initiated subclinical CCL2 secretion and subsequent recruitment of CCR2+ cells, reflecting early immune activation preceding age-associated functional and structural decline. At this stage, cytokine and kinase evaluations indicated a balance between proinflammatory and compensatory signals. However, with aging or following MCMV challenge, this balance shifted towards persistent inflammation, evidenced by chronic upregulation of cytokines and activation of signaling pathways, which ultimately led to adverse effects and myocardial dysfunction. ConclusionsManifestation of genetic cardiomyopathies depends on interactions between inherited susceptibility and environmental stressors. Here, we show that cytomegalovirus infection intensifies inflammation in PKP2-related cardiomyopathy. In contrast, TTN-linked cardiomyopathy does not exhibit increased inflammation under the same conditions. For individuals carrying desmosomal variants, infection control and tailored anti-inflammatory strategies may attenuate or delay disease manifestation and progression.

immunology↗

bioRxiv2025

Single-cell RNA-seq using UltraMarathonRT expands theknown transcriptome

The ability to map messenger RNA (mRNA) molecules from individual cells using next-generation sequencing technologies, known as single-cell RNA-seq (scRNA-seq), is transforming biology by redefining cellular identities with unmatched detail. However, all current protocols depend on copying RNA into complementary DNA with a single reverse transcriptase (RT) derived from murine leukemia virus, which is an RT enzyme known for low processivity and limited ability to unfold complex RNA structures. Here, for the first time, we introduce a group II intron reverse transcriptase, UltraMarathonRT (uMRT), to perform scRNA-seq. We demonstrate that this enzyme reveals an unexpected transcriptomics landscape by capturing additional genes and other genomic features that conventional RTs miss. We also combined uMRT with metabolic RNA labeling, nucleoside conversion and scRNA-seq to explore genome-wide transcriptome dynamics at the single-cell level. Overall, we establish uMRT as a transformative biotechnological tool for single-cell transcriptomics.

molecular biology↗

bioRxiv2024

Prostate-specific membrane receptor PPAP facilitates E. coli invasion of luminal prostate cells via FimH binding

Bacterial prostatitis caused by uropathogenic Escherichia coli (UPEC) strains is a highly prevalent and recurrent infection responsible for significant morbidity in men. However, the molecular pathogenesis of prostatitis remains poorly understood, partly due to the lack of comprehensive in-vitro models. In this study, we introduce a murine prostate organoid model that replicates the cellular heterogeneity of the prostate epithelium with a cell composition and transcriptional signature comparable to the native prostate tissue. Using this model, we uncovered that UPEC preferentially attaches to, invades, and replicates within luminal prostate cells. This selective interaction is mediated by the binding of the bacterial adhesin FimH to the prostate- specific membrane protein PAPP, which is exclusively expressed on luminal prostate cells. Altogether, we identified a new mechanism by which UPEC infects the prostate epithelium, highlighting FimHs adaptability in engaging host receptors and its potential for targeted therapeutic strategies.

molecular biology↗