Biology subjects

Rega, F.

Publications and source records attributed to Rega, F..

3 recordsLinked to original sources

bioRxiv2025

Loss of MGST1 during fibroblast differentiation enhances vulnerability to oxidative stress in human heart failure

BackgroundOxidative stress (OS) resulting from an imbalance between reactive oxygen species (ROS) production and antioxidant defences is a major mechanism exacerbating HF, involving activation of cardiac fibroblasts (FB) and fibrosis. In addition to reducing ROS production and/or scavenging, boosting cellular anti-oxidant capacity is a potential strategy, with FB an interesting target. MethodsWe interrogated single-nucleus RNA sequencing (snRNA-seq) data from human failing and non-failing hearts to identify OS modulating genes. Differential gene expression analysis in FB and comparison with other cell types was used for identification of candidate genes. The functional role of the identified candidate was studied in primary isolated human FB in culture, using knock-down strategies and phenotype manipulation using TGF-{beta}1. ResultsAcross the different cardiac cell types, FB showed the greatest enrichment for OS-modulating genes downregulated in HF. Of these genes, the microsomal glutathione S-transferase 1 (MGST1), was exclusively expressed and downregulated in FB, inversely correlating with elevated ROS levels in HF tissue. TGF-{beta}1 treatment of non-HF FB reduced MGST1 expression. MGST1 knockdown in non-HF FB raised expression of periostin, but not of collagen. ROS production and susceptibility to oxidative damage and lipid peroxidation were also increased. Downregulation of ferroptosis-suppressing and iron-handling genes inversely correlated with MGST1 expression. ConclusionLoss of MGST1 in HF is unique to FB, linked to FB activation. It impairs FB antioxidant capacity, exacerbating oxidative stress, and reduces resistance to ferroptosis. Through these mechanisms, loss of FB MGST1 induces a deleterious positive feedback on cardiac remodelling in human HF.

cell biology↗

bioRxiv2025

Cross-species proteomics quantification pipeline distinguishes donor versus host extracellular matrix in explanted biomaterials

Xenogenic biomaterial durability, including bioprosthetic heart valves (BPVs), is compromised by pathological extracellular matrix (ECM) remodeling, resulting in progressive structural degeneration. Mass spectrometry-based proteomics can help reveal BPV degeneration mechanisms; however, peptide sequence similarity between donor and host species complicates protein-level analysis. We present a cross-species proteomic analytical strategy for xenogenic biomaterials and cross-species proteomic datasets. In silico tryptic digestion of human and bovine protein databases identified over 400 overlapping proteins with a high protein percent identity. Explanted human BPV tissue was divided into macroscopically distinct regions of degeneration and analyzed by mass spectrometry. A peptide-level strategy quantified protein abundances in a species-delineated analysis. We highlighted degeneration region-specific depositions of key human ECM proteins and bovine ECM proteins whose abundance is time dependent. We demonstrated that single-species analysis of a cross-species proteome results in inaccurate quantification. This study highlights the importance of distinguishing between donor and host species proteomes for accurate protein quantification. While focused on clinically explanted biomaterials, our approach is broadly applicable to all forms of xenotransplantation and the use of xenogenic matrices.

bioengineering↗

bioRxiv2025

Early onset of Ca2+ waves and synchronization in multicellular clusters facilitate focal arrhythmogenesis in human heart failure

BackgroundSpontaneous Ca2+ release events and waves are frequent in isolated ventricular cardiomyocytes from failing hearts (HF) and are proposed to initiate arrhythmias in the intact heart. However, evidence supporting whether single-cell Ca2+ waves trigger tissue-wide depolarization in the intact heart is scarce, particularly in human HF. We characterized Ca2+ waves at single-cell resolution within the multicellular network of the intact heart and identified propagating dynamics and mechanisms facilitating arrhythmogenesis at tissue level. MethodsLiving myocardial slices (LMS) from HF and non-HF human hearts were prepared from left ventricular tissue and paced at 2 Hz under adrenergic stimulation. Ca2+ transients and waves were recorded by wide-field imaging of Fluo-8. Ca2+ waves in relation to single-cell structures within each LMS were identified using custom algorithms. Computational modelling assessed whether experimentally observed HF Ca2+ waves dynamics can lead to focal excitation in tissue models. ResultsFollowing pacing, early onset Ca2+ waves, initiating within the first 2 seconds, were more frequent in HF compared to non-HF, and HF cardiomyocytes had more foci, where Ca2+ waves originate, than non-HF. Spatial mapping showed that early onset waves in HF occurred frequently in clusters of neighboring cells. Although early onset Ca2+ waves propagated similar distances in HF and non-HF cardiomyocytes, they more frequently crossed cell boundaries in HF. Particularly, HF LMS exhibited more side-to-side Ca2+ propagation, correlating with increased connexin 43 distribution to lateral membranes. Furthermore, HF LMS exhibited more local and global triggered Ca2+ activities compared to non-HF LMS, correlating with local tissue depolarization. Simulations of HF Ca2+ wave dynamics in remodeled tissue demonstrated a greater capacity to elicit focal excitation. ConclusionsIn human HF, a higher incidence of early onset Ca2+ waves combines with altered intercellular connectivity to create synchrony in clusters of nearby cells that can overcome the current sink, thereby increasing arrhythmia susceptibility. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=70 SRC="FIGDIR/small/651991v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@12582forg.highwire.dtl.DTLVardef@5b9893org.highwire.dtl.DTLVardef@17de348org.highwire.dtl.DTLVardef@1d4c420_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗