Biology subjects

Giordano, L.

Publications and source records attributed to Giordano, L..

7 recordsLinked to original sources

bioRxiv2026

Mitochondrial COX4I2 drives pericyte-dependent inflammation and emphysema

Chronic obstructive pulmonary disease (COPD) is characterized by neutrophilic inflammation, emphysema, and mild pulmonary hypertension (PH). Oxidative/nitrosative stress are key drivers, but specific mitochondrial mechanisms remain unclear. We show increased expression of the regulatory mitochondrial cytochrome c oxidase subunit 4 isoform 2 (COX4I2) in an early murine model and human COPD. After 8 months of cigarette smoke exposure, Cox4i2-/- mice were completely protected from emphysema but not from PH, associated with reduced nitrosative stress, inflammation, and apoptosis. Using a novel Cox4i2 reporter mouse and in situ hybridization of human lungs, COX4I2 was detected in precapillary ACTA2+ cells and capillary pericytes. COX4I2 promotes mitochondrial reactive oxygen species (mtROS) production in these cells, thereby enhancing neutrophil migration and alveolar type II cell apoptosis, and modulates angiogenesis. In contrast to Cox4i2-/-, mitochondria-targeted antioxidant MitoQ reversed emphysema and PH, suggesting pericyte-specific regulation of COPD pathologies and mtROS inhibition as a therapeutic approach in COPD. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=124 SRC="FIGDIR/small/703513v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@83bca4org.highwire.dtl.DTLVardef@d5ebaborg.highwire.dtl.DTLVardef@632d1borg.highwire.dtl.DTLVardef@1267a13_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Exploring the interplay of complex carbohydrate intake, the microbiome CAZymes pool and short-chain fatty acid production in the human gut: insights from different cohorts in the Argentine population

Carbohydrate-active enzyme (CAZyme) activity in the gut microbiome has significant implications for health, including the release of nutrients otherwise inaccessible to the host and the enhancement of digestive efficiency. The primary end products of indigestible carbohydrate fermentation are short-chain fatty acids (SCFAs). We hypothesized that increased dietary fiber consumption could lead to greater SCFA production in the human gut. To investigate this, we examined the relationship between complex carbohydrate intake, CAZyme activity in the human gut microbiome, and SCFA production at the whole metagenomic level across three cohorts: a healthy reference-controlled cohort, an average cohort of individuals living in industrialized cities, and a cohort of patients with inflammatory bowel disease (IBD). Metagenomic sequencing and bioinformatic analyses were utilized to assess the diversity, abundance, and functionality of CAZymes, as well as the metabolic capacity for SCFA production. The average cohort exhibited higher alpha diversity of CAZyme families compared to the reference-controlled cohort, although subfamily composition was similar between both. A moderate negative correlation was identified between CAZyme abundance and SCFA production, indicating that a higher number of these enzymes does not directly translate to increased SCFA synthesis. In IBD patients, a decrease in the diversity and composition of CAZyme subfamilies was observed, suggesting a disruption in enzymatic functions associated with the disease. However, the overall functionality of CAZymes remained relatively stable across different health conditions, highlighting the resilience of the gut microbiome for these functions. These findings deepen our understanding of the gut microbiomes role in health and disease, emphasizing that despite variations in microbial diversity, key enzymatic functions persist. The study underscores the complexity of the non-linear relationship between complex carbohydrate metabolism and SCFA production, laying the groundwork for future research on microbiome-targeted therapeutic/dietary profile interventions in both non-disease and chronic diseases conditions.

genomics↗

bioRxiv2025

Gut microbial-derived short chain fatty acids enhance kidney proximal tubule cell secretory function

The organic anion transporter-1 (OAT1), located at the basal side of kidney proximal tubule cells, is actively involved in metabolic waste excretion. During chronic kidney disease (CKD), the progressive decline in renal function, results in the accumulation of endogenous metabolites in the bloodstream, exacerbating comorbidities. CKD also leads to gut dysbiosis, resulting in an increased production of uremic metabolites and a reduced production of nephroprotective short chain fatty acid (SCFAs), mainly acetate, propionate and butyrate, thereby contributing to disease progression. Here, we studied the potential of SCFAs to enhance kidney function by modulating OAT1 activity, thereby facilitating uremic toxins secretion. Our findings demonstrate that propionate and butyrate significantly boost OAT1 activity by upregulating SLC22A6/ OAT1 gene and protein expression, with butyrate enhancing the secretion of the uremic toxin indoxyl sulfate to the luminal compartment in our kidney-on-chip (KoC) system. Interestingly, SCFAs function independently of G-protein coupled receptor (GPCR) activation, inhibiting gene expression of class II histone deacetylases (HDACs). Transcriptome analysis suggests that such inhibition modulates cyclic AMP signaling pathway, activating CREB1 and PI3K gene expression, both implicated in cell metabolism and resilience against stress, enhancing cellular fitness. These findings highlight the therapeutic potential of SCFAs in enhancing proximal tubule secretory activity, emphasizing their value as nutritional interventions in CKD management. HIGHLIGHTSO_LIOAT1 activity is boosted by SCFAs via SLC22A6 gene and protein upregulation C_LIO_LISCFAs act independently of GPCRs activation in proximal tubule cells C_LIO_LIHDAC inhibition by SCFAs regulates cAMP pathway modulating CREB1 and PI3K expression C_LIO_LISCFAs have the potential to serve as a therapeutic approach for kidney disease treatment C_LI

pharmacology and toxicology↗

bioRxiv2025

Dynamic balance of H3K9me2 heterochromatin by CoREST-2 and RE-1 in growing neurons

A well-balanced chromatin dynamic is vital for the survival and physiology of all cells, including brain neurons. Heterochromatin, commonly associated with transcriptional silencing, also plays significant roles in maintaining genomic stability and facilitating DNA-repair processes. Notably, the bimethylation of histone H3 at lysine 9 (H3K9me2), a hallmark of repressive heterochromatin, supports the axonal specification of neurons. However, neuronal maintenance of H3K9me2 equilibrium remains understudied. In this work, we unveil a dynamic equilibrium of H3K9me2 regulated by the epigenetic factor CoREST-2 and RE-1 DNA motifs, sustaining axonal and dendritic outgrowth. Using primary cultures of rat hippocampal neurons and a combination of advanced imaging techniques, we observed an enriched nuclear accumulation of CoREST-2 and H3K9me2 along neuronal development. Genetic silencing of CoREST-2 induced axon-dendrite retraction, accompanied by an increase in nuclear levels of H3K9me2. To further investigate heterochromatin structure at the nanoscale, we employed STED nanoscopy and discovered that H3K9me2 is organized into small nanodomains, which were notably enlarged following the suppression of CoREST-2. In contrast, the genetic blockade of RE-1 DNA motifs led to axon-dendrite retraction alongside the disassembly of H3K9me2 nanodomains. These findings highlight that CoREST-2 and RE-1 sites actively shape neuronal H3K9me2 heterochromatin. Moreover, they uncover that maintaining a precise balance of H3K9me2 is essential for the extension of axons and dendrites, underpinning the connectivity and plasticity of brain neurons.

cell biology↗

bioRxiv2022

Antibodies to Coagulase of Staphylococcus aureus crossreact to Efb and reveal different binding of shared Fibrinogen Binding repeats

Staphylococcus aureus pathology is caused by a plethora of virulence factors able to combat multiple host defence mechanisms. Fibrinogen (Fg), a critical component in the host coagulation cascade, plays an important role in the pathogenesis of this bacterium, as it is the target of multiple staphylococcal virulence proteins. Amongst its secreted virulence factors, Coagulase (Coa) and Extracellular fibrinogen-binding protein (Efb) share common Fg binding motives and have been described to form a Fg shield around staphylococcal cells, thereby allowing efficient bacterial spreading, phagocytosis escape and evasion of host immune system responses. Targeting these proteins with monoclonal antibodies thus represents a new therapeutic option against S. aureus. To this end, here we report the selection and characterization of fully human, sequence-defined, monoclonal antibodies selected against the C-terminus of Coagulase. Given the functional homology between Coa and Efb, we also investigated if the generated antibodies bound the two virulence factors. Thirteen unique antibodies were isolated from naive antibodies gene libraries by antibody phage display. As anticipated, most of the selected antibodies showed cross-recognition of these two proteins and among them, four were able to block the interaction between Coa/Efb and Fg. Furthermore, our monoclonal antibodies could interact with the two main Fg binding repeats present at the C-terminus of Coa and distinguish them, suggesting the presence of two functionally different Fg-binding epitopes. ImportanceThe death toll related to methicillin-resistant S. aureus piled to almost 1 million people in only one year (2019), ascribing S. aureus to the second leading cause of deaths associated with antimicrobial resistance. Therefore, new therapeutic strategies must be investigated. Blocking the adhesion step with the use of monoclonal antibodies is one promising alternative and Fg is a central plasma protein involved in staphylococcal infection. We present here a panel of monoclonal antibodies raised against Coa, cross-reacting to Efb and targeting the shared Fg binding repeats of Coa. In addition, we describe new epitope determinants in the repeated region of Coa, highlighted by differential binding of the newly selected antibodies.

biochemistry↗

bioRxiv2021

Extracellular release of mitochondrial DNA is triggered by cigarette smoke and is detected in COPD

Chronic obstructive pulmonary disease (COPD) is characterized by continuous and irreversible inflammation frequently caused by persistent exposure to toxic inhalants such as cigarette smoke (CS). CS may trigger mitochondrial DNA (mtDNA) extrusion into the cytosol, extracellular space, or foster its transfer by extracellular vesicles (EVs). The present study aimed to elucidate whether mtDNA is released upon CS exposure and in COPD. We measured cell-free mtDNA (cf-mtDNA) in the plasma of former smokers affected by COPD, in the serum of mice that developed CS-induced emphysema, and in the extracellular milieu of human bronchial epithelial cells exposed to cigarette smoke extract (CSE). Further, we characterized cells exposed to sublethal and lethal doses of CSE by measuring mitochondrial membrane potential and dynamics, superoxide production and oxidative stress, cell cycle progression, and cytokine expression. Patients with COPD and mice that developed emphysema showed increased levels of cf-mtDNA. In cell culture, exposure to a sublethal dose of CSE decreased mitochondrial membrane potential, increased superoxide production and oxidative damage, dysregulated mitochondrial dynamics, and triggered mtDNA release in extracellular vesicles. The release of mtDNA into the extracellular milieu occurred concomitantly with increased expression of DNase III, DNA-sensing receptors (cGAS, NLRP3), proinflammatory cytokines (IL-1{beta}, IL-6, IL-8, IL-18, CXCL2), and markers of senescence (p16, p21). Exposure to a lethal dose of CSE preferentially induced mtDNA and nuclear DNA release in cell debris. Our findings demonstrate that CS-induced stress triggers mtDNA release and is associated with COPD, supporting cf-mtDNA as a novel signaling response to CS exposure.

cell biology↗

bioRxiv2020

An automated, high throughput methodology optimized for quantitative cell-free mitochondrial and nuclear DNA isolation from plasma

Circulating, cell-free mitochondrial DNA (ccf-mtDNA) and nuclear DNA (ccf-nDNA) are under investigation as biomarkers for various diseases. Optimal ccf-mtDNA isolation parameters, like those outlined for ccf-nDNA, have not been established. Here, we optimized a protocol for both ccf-mtDNA and ccf-nDNA recovery using a magnetic bead-based isolation process on an automated 96-well platform. Using the optimized protocol, our data show 6-fold improved yields of ccf-mtDNA when compared to the starting protocol. Digestion conditions, liquid handling characteristics, and magnetic particle processor programming all contributed to increased recovery and improved reproducibility. To our knowledge, this is the first high-throughput approach optimized for mtDNA and nDNA recovery and serves as an important starting point for clinical studies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=191 HEIGHT=200 SRC="FIGDIR/small/206987v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@13ab547org.highwire.dtl.DTLVardef@1535020org.highwire.dtl.DTLVardef@b191aaorg.highwire.dtl.DTLVardef@1d23fa4_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗