Biology subjects

Sussman, C.

Publications and source records attributed to Sussman, C..

7 recordsLinked to original sources

bioRxiv2026

Lung hypoperfusion stimulates liquid absorption in alveoli

Tissue hypoperfusion is common in clinical settings, but how tissues respond to hypoperfusion on a microphysiological scale is not clear. We used real-time confocal microscopy of live, perfused lungs to gain insights into the effects of hypoperfusion on the microcirculation and microphysiology of lung alveoli, where gas exchange occurs. We focused on effects of hypoperfusion on alveolar liquid secretion, since alveolar liquid secretion is important for alveolar homeostatic functions. Our findings show lung hypoperfusion stimulated a reversal of alveolar liquid transport, from homeostatic liquid secretion to absorption. Specifically, lung perfusion at or near physiological perfusion pressure led to alveolar liquid secretion that depended on the alveolar epithelial cystic fibrosis transmembrane conductance regulator (CFTR), Na+-K+-Cl- cotransporters, and the Na+/K+-ATPase. Within minutes of halting lung perfusion or majorly reducing it, alveoli stopped secreting liquid and instead absorbed it via the epithelial Na+ channel, CFTR, and K+-Cl- cotransporters. We provide evidence that hypoperfusion caused alveolar microvessel lumens to shrink and airspaces to expand, leading to epithelial stretch that stimulated liquid absorption. These findings show lung hypoperfusion initiates mechanical signals that stimulate the alveolar epithelium to absorb liquid, and they may inform the pathogenesis of lung diseases characterized by acute microvascular hypoperfusion.

physiology↗

bioRxiv2026

Chronic TGFβ1 Signaling Drives Aberrant Alveolar-Basaloid Metaplasia through a KRT17-Stratifin migratory complex

Chronic fibrotic disorders like idiopathic pulmonary fibrosis (IPF) are characterized by aberrant alveolar regeneration and severely limited treatment options. Identification of the mechanisms driving aberrant epithelial repair can lead to new viable therapeutic targets. Using integrated single nucleus ATAC- and RNA-sequencing on human lungs and an in vitro model of dysplastic repair, we identify two distinct regenerative trajectories for alveolar type 2 (AT2) cells: a resolvable euplastic repair trajectory and a persistent, non-resolving dysplastic repair trajectory. The latter is governed by a spatially restricted ITGB6/TGF {beta} 1/SMAD3 signaling axis in fibrotic regions of IPF lungs and in murine lungs characterized by chronic epithelial remodeling. Mechanistically, SMAD3 directly regulates dysplastic transitional cell (DTC) markers, including KRT17 and Stratifin. We show that TGF {beta} 1-induced physical interaction between KRT17 and Stratifin at the leading edge of migrating DTCs is essential for their migration. These findings collectively define the molecular regulation of AT2-driven dysplastic regeneration and identify TGF {beta} 1-induced KRT17-Stratifin axis as a central driver of AT2 remodeling and their migration in chronic fibrosis, highlighting a therapeutically targetable signaling axis.

cell biology↗

bioRxiv2026

Notch mediates non-regenerative alveolar repair after staphylococcal lung injury

Severe lung infection causes dysfunction of the lungs air-blood barrier, leading to respiratory failure. In alveoli of lungs infected with Staphylococcus aureus (SA) - either alone or after respiratory viral infection - the SA toxin, alpha hemolysin (Hla) causes epithelial barrier protein degradation and airspace edema formation. How the barrier repairs is not clear. We used confocal imaging of intact, perfused, SA-infected lungs to define barrier repair mechanisms in live alveoli. Though we expected to find the non-surviving alveolar epithelium was regenerated, we found, instead, the surviving alveolar epithelium spontaneously regained barrier function. Thus, SA stimulated Notch protein cleavage in the alveolar epithelium in an Hla- and ADAM10-dependent manner. Subsequent exposure of the Notch transmembrane domain catalyzed epithelial junctional protein recovery to reseal the barrier and restore barrier integrity. While disrupting Notch cleavage in the alveolar epithelium prolonged SA-induced lung injury, augmenting it accelerated lung repair. We interpret that barrier repair in the surviving alveolar epithelium resulted from Notch-mediated junctional protein reassembly. These findings show, for the first time, that the alveolar epithelium is a resilient tissue that harbors robust endogenous repair mechanisms. We propose strategies that leverage Notchs non-regenerative, barrier-strengthening capability may promote lung repair after staphylococcal lung infection.

molecular biology↗

bioRxiv2025

Multivalent Nanobodies for Potent and Broad Neutralization of Staphylococcus aureus Toxins

Staphylococcus aureus is a leading cause of lethal bacteremia and pneumonia, which are driven by potent virulence factors such as T-cell superantigens and alpha hemolysin. S. aureus has among the highest rates of antibiotic resistance, yet no vaccines or alternative therapies are available despite decades of research. Here, we developed a repertoire of potent, high affinity nanobodies (Nbs) targeting key toxins in S. aureus infection, including superantigens (SAgs) SEB, SEC, TSST-1, and Hla. Comprehensive cryo-EM and AlphaFold3 analyses of these Nbs, which were elicited with clinical cocktail vaccines, revealed diverse neutralizing epitopes and mechanisms that provide strategic insights for immunotherapy and vaccine design. Guided by these findings, we engineered highly stable, multivalent, and multifunctional Nb constructs. These constructs included an aerosolizable trimeric Nb with enhanced neuralization activity against Hla and SEC, and an ultrapotent decameric Nb-IgG-Fc fusion construct against a wide range of major toxins in S. aureus sepsis (SEB, SEC, TSST-1, and Hla). These multifunctional Nbs demonstrated promising protective activity in murine models of pneumonia and sepsis, underscoring their potential as versatile immunotherapies that address the complex virulence profiles of S. aureus. Our work lays a foundation for precision immunotherapies beyond current treatment options to combat complex bacterial infections with multiple virulence mechanisms. Significance statementS. aureus is among the most common, antibiotic-resistant, and deadly causes of bacterial infections. We developed nanobodies against clinically significant virulence factors in S. aureus sepsis and pneumonia, including superantigens (SAgs) SEB, SEC, and TSST-1 as well as pore forming toxin Hla. These nanobodies displayed complete and potent neutralization of each toxin, exploiting a wide variety neutralizing mechanisms. Structural investigation of these diverse neutralizing nanobodies, which were elicited in llamas using clinically investigated cocktail vaccines, highlighted the importance of disrupting SAg interaction with TCR or MHCII and potential flaws in targeting poorly neutralizing conserved SAg epitopes using vaccine cocktails. Nb leads against each toxin were combined in different multivalent configurations, including an aerosolizable trimeric Nb and a half-life extended decameric Nb IgG Fc fusion construct. This work highlights multivalent nanobodies as a comprehensive yet therapeutically precise drug platform that addresses the complex virulence profiles of bacterial infectious diseases.

microbiology↗

bioRxiv2025

DNA-based delivery of incretin receptor agonists using MYO Technology leads to durable weight loss in a diet-induced obesity model

Therapeutic proteins have seen a substantial increase in clinical development and use across many disease areas. Despite their broad applicability, significant drawbacks limit access to many of these drugs, including: i) high manufacturing costs; ii) administration via time-consuming infusions; iii) frequent dosing, sometimes even daily; and iv) requirements for low temperature storage. MYO Technology was developed to overcome these barriers. The MYO Technology platform consists of therapeutic-encoding plasmid DNA (pDNA), and a proprietary medical device for intramuscular injection and delivery of electrical pulses. These pulses enable the in vivo electroporation of muscle cells and uptake of injected pDNA, leading to the production, secretion, and delivery of the therapeutic protein into peripheral circulation. MYO Technology offers several advantages over standard delivery of therapeutic proteins; pDNA manufacturing is a simpler and less specialized process compared to protein manufacturing, and pDNA is very stable and lacks most cold chain requirements. Furthermore, administration using MYO Technology takes only a few minutes, and the serum level of a therapeutic protein can potentially be maintained for many months without the need for redosing. Incretin receptor agonists (IRAs) are a class of therapeutic proteins that have recently come to prominence as powerful weight and glucose control drugs, and are used for the treatment of type 2 diabetes (T2D) and obesity. Semaglutide and tirzepatide, currently the most widely used within this class, are both potent molecules, but have a short half-life, requiring weekly administration by subcutaneous injections. Moreover, since their clinical benefits rapidly disappear upon treatment cessation, T2D and obese patients may have a life-long dependency on IRAs, and the requirement for weekly injections can negatively affect the quality of life and the adherence to therapy, as well as create a significant financial burden. Therefore, increasing the interval between injections has become one of the major goals in the field. Here, we present our preclinical studies on the delivery of IRAs with MYO Technology. Animal proof-of-concept studies demonstrate that MYO Technology-delivered IRAs are functional, and efficacious in promoting long-lasting weight and glucose control in mouse models of diet-induced obesity. Moreover, engineering the IRAs to facilitate blood-brain barrier penetration further enhances treatment efficacy, with benefits persisting beyond one year following a single administration. Together, these findings highlight MYO Technologys potential to transform care for patients with T2D and obesity by enabling long-lasting therapeutic effects with minimal dosing, ultimately improving quality of life and treatment adherence.

physiology↗

bioRxiv2025

CFTR function in alveolar type 1 cells drives lung liquid secretion and host defense

Loss of the liquid layer that lines the lungs air-facing surface underpins mechanisms of major lung diseases, but the development of therapies that restore liquid secretion is hampered by an incomplete understanding of the cell types that drive it. Here, we show CFTR function in alveolar type 1 (AT1) cells - a cell type that comprises 95% of the lung surface but is presumed to be unimportant in CFTR-related diseases - is critical to lung liquid secretion and the secretion-mediated clearance of particles and S. aureus from lung alveoli. Our findings reveal essential roles for AT1 cells in lung homeostasis and defense, and they call for a reevaluation of the role of AT1 cells in CFTR-related diseases. We suggest AT1 cells be considered key targets of secretion-restoring therapies.

cell biology↗

bioRxiv2024

A deep-learning tool for species-agnostic integration of cancer cell states

Genetically engineered mouse models (GEMM) of cancer are a useful tool for exploring the development and biological composition of human tumors and, when combined with single-cell RNA-sequencing (scRNA-seq), provide a transcriptomic snapshot of cancer data to explore heterogeneity of cell states in an immunocompetent context. However, cross-species comparison often suffers from biological batch effect and inherent differences between mice and humans decreases the signal of biological insights that can be gleaned from these models. Here, we develop scVital, a computational tool that uses a variational autoencoder and discriminator to embed scRNA-seq data into a species-agnostic latent space to overcome batch effect and identify cell states shared between species. We introduce the latent space similarity (LSS) score, a new metric designed to evaluate batch correction accuracy by leveraging pre-labeled clusters for scoring instead of the current method of creating new clusters. Using this new metric, we demonstrate scVital performs comparably well relative to other deep learning algorithms and rapidly integrates scRNA-seq data of normal tissues across species with high fidelity. When applying scVital to pancreatic ductal adenocarcinoma or lung adenocarcinoma data from GEMMs and primary patient samples, scVital accurately aligns biologically similar cell states. In undifferentiated pleomorphic sarcoma, a test case with no a priori knowledge of cell state concordance between mouse and human, scVital identifies a previously unknown cell state that persists after chemotherapy and is shared by a GEMM and human patient-derived xenografts. These findings establish the utility of scVital in identifying conserved cell states across species to enhance the translational capabilities of mouse models.

cancer biology↗