David Marciano

Pulmonary arterial hypertension (PAH) is a progressive pulmonary vasculopathy in which endothelial dysfunction drives increased pulmonary vascular resistance and arterial remodeling. Redox signaling is central to endothelial homeostasis, and its disruption in PAH reflects changes in the magnitude, source, and subcellular location of reactive oxygen species (ROS) production, as well as the molecular targets they engage. In healthy endothelium, compartmentalized redox signaling supports adaptive responses while preserving nitric oxide bioavailability. Loss of this spatial control in PAH can convert normally transient redox signals into persistent endothelial dysfunction, although the strength of evidence for this conversion differs substantially between pathways. This review examines how disease-associated stressors reshape endothelial redox signaling through NADPH oxidases, mitochondria, eNOS, iron-dependent chemistry, and nuclear pathways and how these compartments communicate. We also examine emerging circulating markers of redox and endothelial dysfunction and evaluate redox-directed therapies across experimental pulmonary hypertension and PAH. Throughout, we grade each mechanism according to whether it is supported by evidence from human PAH vascular tissue, patient-derived pulmonary arterial endothelial cells, experimental pulmonary hypertension models, and pulmonary endothelial models or by extrapolation from other relevant disease systems, and we identify where compartment-specific evidence is inferred from enzyme localization rather than measured directly. Current evidence supports moving beyond broad antioxidant approaches toward strategies that selectively target pathogenic redox signaling within the relevant endothelial compartment.

Redox homeostasis requires both inducible antioxidant defense and constitutive machinery that continuously regenerates cellular reducing capacity. How these systems are altered across lung cell populations in chronic obstructive pulmonary disease (COPD) remains unclear. We integrated donor-level single-nucleus lung transcriptomes with smoke-exposure models, independent cohorts, and large-scale pharmacologic perturbation data. Both redox programs were reduced in established COPD, but constitutive redox support showed the greater loss, concentrated in fibroblasts and lymphatic endothelium. In fibroblasts, PGC-1α target-program output showed the most negative effect among 515 regulator programs despite preserved PPARGC1A expression. Smoke exposure activated inducible antioxidant defense across experimental models, whereas this adaptive program was reduced in established COPD. Pharmacologic perturbations further separated the two arms of redox homeostasis, with redox-directed interventions producing larger transcriptional responses in inducible defense and a distinct set of compounds increasing constitutive support together with PGC-1α target output and movement away from an independently defined COPD fibroblast state. These findings identify a cell-selective loss of constitutive redox support in COPD and implicate reduced PGC-1α target-program output in the fibroblast redox phenotype.

Pulmonary arterial hypertension (PAH) is associated with increased oxidative DNA damage, while haploinsufficiency of BMPR2 and other dosage-sensitive genes contributes directly to disease. Template-strand 8-oxoguanine (8-oxoG) provides a potential transient route to the same loss-of-function outcome through transcriptional mutagenesis without altering genomic DNA. RNA polymerase II can insert adenine opposite the lesion and generate a coding-sense C>A error in the nascent transcript. We asked whether this chemistry could generate premature-stop transcripts in dosage-sensitive PAH genes. Across 17,880 C>A-accessible coding positions in pulmonary vascular genes, 1,192 could generate premature termination codons, including 883 predicted to engage nonsense-mediated decay (NMD). Restricting these sites to expressed autosomal-dominant PAH genes with definitive ClinGen validity and established haploinsufficiency identified 116 NMD-prone positions in BMPR2, KDR, SMAD9, and TBX4. Eight exactly reproduce ClinVar pathogenic or likely pathogenic stop variants, including five in BMPR2. At BMPR2 c.1424, template-strand 8-oxoG and the expert-panel-reviewed genomic c.1424C>A allele is predicted to generate the same UAA-containing transcript. Published oxidized-guanine maps detect signal at seven of the eight coordinates, providing coordinate-level support for oxidative modification at these sites. These findings define a sequence-resolved route through which repairable oxidative DNA damage could transiently reproduce loss-of-function transcripts encoded by pathogenic PAH alleles without permanent genomic mutation.

8-Oxoguanine (8-oxoG) is a common oxidative DNA lesion that can alter coding output during transcription without changing the underlying DNA sequence. When present on the template strand, 8-oxoG can direct RNA polymerase II to insert adenine, generating a transient coding-sense C>A error restricted by the genetic code to 18 directional amino-acid substitutions. Mapping these substitutions onto ClinVar identified 3,910 disease-associated protein states across 1,333 genes, representing 5.7% of evaluable pathogenic or likely pathogenic missense states. In 211 cases, transcriptional miscoding and the corresponding genomic disease variant affect different nucleotides within the same codon yet converge on the same amino acid substitution, allowing the disease-associated protein state to arise while the implicated genomic nucleotide remains wild type. Accessible states were enriched among genes with post-mitotic expression and neurological disease annotation, particularly in neuronal signaling pathways. Published oxidized-guanine maps supported 2,146 accessible genomic coordinates, while human proteogenomic data contained 78 exact codon-compatible protein states not explained by sample-specific transcript sequence. Together, these analyses define a chemically constrained set of disease-associated protein states accessible through 8-oxoG transcriptional miscoding without permanent genomic mutation.

N6-methyladenosine (m⁶A) represents the most abundant and tightly controlled modification within eukaryotic mRNA, critically influencing RNA metabolism and function. The m⁶A methyltransferase Like-3 (METTL3), responsible for the complex’s catalytic function, has emerged as a central epitranscriptomic regulator governing mRNA stability, alternative splicing, nuclear export, and the efficiency of mRNA translation. Converging research shows that METTL3 is involved in the pathogenesis of numerous disorders via m⁶A-dependent, post-transcriptional regulation of gene programs controlling cell growth, migration, and immune pathways. Regarding pulmonary pathophysiology, METTL3-mediated m⁶A is tied to disease initiation and progression in conditions such as asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), lung infections, acute respiratory distress syndrome (ARDS). This review summarizes the contemporary evidence for METTL3’s roles and regulatory network in diverse pulmonary pathologies. We further highlight emerging strategies for targeting METTL3 as a potential therapeutic approach, underscoring its promise as a novel epitranscriptomic target. Beyond inflammatory and fibrotic disorders, we also summarize emerging evidence linking METTL3 to lung cancer and briefly outline other respiratory conditions (e.g., ILD, bronchiectasis, and secondary pulmonary hypertension), highlighting common translational themes and remaining gaps. Further studies are required to clarify the disease-specific and context-dependent actions of METTL3 and to advance the clinical translation of m⁶A-based therapies.

The environmental fragmentation of plastic waste leads to the formation of micro- and nanoplastics (MNPs), which pose serious ecological and human health concerns. Despite increasing interest in their biological effects, many studies rely on artificial, uniform particles that fail to mimic the diverse physical and chemical characteristics of real-world MNPs. To address this limitation, we developed the Accelerated Plastic Aging in Suspension (APAS) system—a scalable, reproducible method that mimics natural aging processes by combining ultraviolet (UV) radiation, thermal stress, and mechanical shear to generate environmentally relevant MNPs from commonly used polymers. We used APAS to fragment polyethylene terephthalate (PET), polyamide 6 (Nylon), and polyacrylonitrile (PAN), and observed time-dependent degradation, including the spontaneous formation of nanoplastics (<100 nm). Flow cytometry revealed substantial increases in particle number and reductions in average particle size over 12 weeks. Imaging flow cytometry confirmed consistent generation of heterogeneous, irregular particles across replicate batches. High-resolution imaging via AFM, TEM, and SEM confirmed the presence of nanoplastics with textured and irregular morphologies. Chemical characterization showed APAS aging altered particle surface charge and induced polymer-specific changes in autofluorescence and Raman spectral profiles, consistent with oxidative surface modifications. Laser Direct Infrared (LDIR) imaging further confirmed structural and chemical changes in polymer spectra post-aging. Functionally, under physiologically relevant shear flow conditions, endothelial cells internalized APAS-generated PET MNPs at significantly higher levels than polystyrene (PS) beads of similar size. Uptake was enhanced particularly under oscillatory flow, highlighting the influence of particle physicochemical properties on cellular interactions. Together, these findings demonstrate the ability of the APAS system to produce complex and realistic MNPs for use in environmental and toxicological studies. The system enables generation of nanoplastics and supports more accurate modelling of biological exposure scenarios compared to conventional synthetic particles.

Mechanical ventilation (MV) is a life-supporting strategy employed in the Intensive Care Unit (ICU). However, MV-associated mechanical stress exacerbates existing lung inflammation in ICU patients, resulting in limited improvement in mortality and a condition known as Ventilator-Induced Lung Injury (VILI). Sphingosine-1-phosphate (S1P) is a circulating bioactive lipid that maintains endothelial integrity primarily through S1P receptor 1 (S1PR1). During VILI, mechanical stress upregulates endothelial S1PR3 levels. Unlike S1PR1, S1PR3 mediates endothelial barrier disruption through Rho-dependent pathways. However, the specific impact of elevated S1PR3 on lung endothelial function, apart from Rho activation, remains poorly understood. In this study, we investigated the effects of S1PR3 in endothelial pathobiology during VILI using an S1PR3 overexpression adenovirus. S1PR3 overexpression caused cytoskeleton rearrangement, formation of paracellular gaps, and a modified endothelial response towards S1P. It resulted in a shift from S1PR1-dependent barrier enhancement to S1PR3-dependent barrier disruption. Moreover, S1PR3 overexpression induced an ADAM10-dependent cleavage of Vascular Endothelial (VE)-cadherin, which hindered endothelial barrier recovery. S1PR3-induced cleavage of VE-cadherin was at least partially regulated by S1PR3-mediated NFκB activation. Additionally, we employed an S1PR3 inhibitor TY-52156 in a murine model of VILI. TY-52156 effectively attenuated VILI-induced increases in bronchoalveolar lavage cell counts and protein concentration, suppressed the release of pro-inflammatory cytokines, and inhibited lung inflammation as assessed via a histological evaluation. These findings confirm that mechanical stress associated with VILI increases S1PR3 levels, thereby altering the pulmonary endothelial response towards S1P and impairing barrier recovery. Inhibiting S1PR3 is validated as an effective therapeutic strategy for VILI.

RNA polymerase III (Pol III) includes two alternate isoforms, defined by mutually exclusive incorporation of subunit POLR3G (RPC7α) or POLR3GL (RPC7β), in mammals. The contributions of POLR3G and POLR3GL to transcription potential has remained poorly defined. Here, we discover that loss of subunit POLR3G is accompanied by a restricted repertoire of genes transcribed by Pol III. Particularly sensitive is snaR-A, a small noncoding RNA implicated in cancer proliferation and metastasis. Analysis of Pol III isoform biases and downstream chromatin features identifies loss of POLR3G and snaR-A during differentiation, and conversely, re-establishment of POLR3G gene expression and SNAR-A gene features in cancer contexts. Our results support a model in which Pol III identity functions as an important transcriptional regulatory mechanism. Upregulation of POLR3G, which is driven by MYC, identifies a subgroup of patients with unfavorable survival outcomes in specific cancers, further implicating the POLR3G-enhanced transcription repertoire as a potential disease factor.

We previously reported heightened expression of the human endogenous retroviral protein HERV-K deoxyuridine triphosphate nucleotidohydrolase (dUTPase) in circulating monocytes and pulmonary arterial (PA) adventitial macrophages of patients with PA hypertension (PAH). Furthermore, recombinant HERV-K dUTPase increased IL-6 in PA endothelial cells (PAECs) and caused pulmonary hypertension in rats. Here we show that monocytes overexpressing HERV-K dUTPase, as opposed to GFP, can release HERV-K dUTPase in extracellular vesicles (EVs) that cause pulmonary hypertension in mice in association with endothelial mesenchymal transition (EndMT) related to induction of SNAIL/SLUG and proinflammatory molecules IL-6 as well as VCAM1. In PAECs, HERV-K dUTPase requires TLR4-myeloid differentiation primary response–88 to increase IL-6 and SNAIL/SLUG , and HERV-K dUTPase interaction with melanoma cell adhesion molecule (MCAM) is necessary to upregulate VCAM1 . TLR4 engagement induces p-p38 activation of NF- κ B in addition to p-pSMAD3 required for SNAIL and pSTAT1 for IL-6 . HERV-K dUTPase interaction with MCAM also induces p-p38 activation of NF- κ B in addition to pERK1/2-activating transcription factor-2 (ATF2) to increase VCAM1 . Thus in PAH, monocytes or macrophages can release HERV-K dUTPase in EVs, and HERV-K dUTPase can engage dual receptors and signaling pathways to subvert PAEC transcriptional machinery to induce EndMT and associated proinflammatory molecules.