Biology subjects

Gurczynski, S. J.

Publications and source records attributed to Gurczynski, S. J..

6 recordsLinked to original sources

bioRxiv2026

Cell-Specific Modulation of the Aryl Hydrocarbon Receptor by Kynurenine in Pulmonary Fibrosis Requires Microenvironmental Crosstalk

BackgroundIdiopathic pulmonary fibrosis (IPF) is a progressive, chronic lung disease with limited therapeutic options. Tryptophan metabolism is significantly dysregulated during lung fibrogenesis, with the metabolite kynurenine (kyn) accumulating in lung tissue and driving pathology via the aryl hydrocarbon receptor (AHR). This study evaluates the cell-specific contributions of kyn-mediated AHR signaling across different pulmonary cell types to clarify its role in disease progression. MethodsUsing a murine model of bleomycin-induced pulmonary fibrosis, lung tryptophan metabolites were profiled via liquid chromatography-mass spectrometry. The functional and transcriptomic impacts of kyn administration and AHR modulation were subsequently characterized across three distinct cellular compartments: CD103+ dendritic cells (DCs), fibroblasts, and alveolar epithelial cells (AECs). ResultsKyn levels were elevated in fibrotic lungs, and exogenous kyn selectively exacerbated collagen deposition during the fibrogenic phase rather than altering acute injury. In vitro monocultures of primary lung fibroblasts and AECs revealed negligible functional responses to kyn or AHR inhibition regarding myofibroblast differentiation, migration, or epithelial barrier disruption. Intriguingly, primary tissue-resident CD103+ DCs exhibited a hyperinflammatory, non-canonical AHR signaling profile in vivo. While ex vivo monoculture rapidly reverted these DCs to an anti-inflammatory, canonical AHR state, directly co-culturing DCs with fibrotic primary lung fibroblasts successfully restored the pathogenic, non-canonical signaling phenotype characterized by augmented IL-6 production and suppressed canonical targets. ConclusionsPathogenic AHR signaling in pulmonary fibrosis is highly cell-context dependent and driven by complex cell-cell interactions. Reductionist monocultures fail to replicate tissue- level dendritic cell phenotypes, highlighting the necessity of co-culture models and providing a cautionary note for the systemic clinical use of AHR-targeted therapeutics.

immunology↗

bioRxiv2025

Toxoplasma induced cytokine release syndrome is critically dependent on the expression of pore-forming Perforin-Like Protein-1

Acute virulence in Toxoplasma gondii is linked to an excessive proinflammatory cytokine cascade during laboratory murine infection. Previous work showed that T. gondii secretes a pore forming protein, PLP1, that is required for efficient cytolytic egress from host cells. Deletion of the PLP1 gene results in defective egress from infected culture cells and a marked reduction in parasite virulence. The goal of the present study was to gain insight into the nature of the attenuated virulence observed in PLP1 knockout compared to wild type (WT) RH parasites. Using in vivo bioluminescence imaging, we show that parasites lacking PLP1 establish an acute infection and disseminate throughout the infected mice. Histological tissue analysis indicates that parasites cause severe pathology, even in the absence of PLP1. However, mice infected with{Delta} plp1 parasites evoke a protective inflammatory response, demonstrated by mouse survival and control of infection. Flow cytometric analysis was used to determine cellular changes occurring during both WT and {Delta}plp1 parasite infection. Parasite control in the{Delta} plp1 infection was associated with earlier activation of myeloid cells and a moderate neutrophil response that, by comparison, becomes the dominant infiltrating cell type of WT infection. Positive disease outcome during{Delta} plp1 parasite infection is also associated with regulated induction of proinflammatory cytokines, including IFN-{gamma} and TNF-, and an earlier IL-10 regulatory response that is dysregulated during WT infection. Together these findings suggest a key role for Toxoplasma PLP1 in promoting a lethal inflammatory immune response during acute infection with a virulent strain of the parasite. Author SummaryPore-forming proteins are virulence determinants expressed by multiple different pathogens, with varied roles including cellular invasion and escape, immune cell destruction, and the hijack of host cell defenses. The pathogen, Toxoplasma gondii, expresses a pore-forming protein PLP1, that is required for cell lysis and acute virulence in mice. Here, we investigate the potential mechanisms by which this pore-forming protein promotes parasite virulence; from parasite replication and dissemination to immunologic outcomes after infection. In vivo infections demonstrate that parasites replicate, disseminate, and stimulate a protective immune response when PLP1 is not expressed. We show that PLP1 expression induces a parasite driven dysregulation of cell populations and cytokine/chemokine responses, resulting in cytokine release syndrome. In a broader context, Toxoplasmas PLP1 is comparable to other pathogen pore-forming proteins that function as virulence determinants by their ability to alter host immune responses.

microbiology↗

bioRxiv2024

Lung Microbiome Intervention Attenuates Herpesvirus-Induced Post-HCT Pulmonary Fibrosis Through PD-L1 Upregulation on Dendritic Cells

Alterations in the lung microbiome frequently accompany adverse pulmonary outcomes. Hematopoietic cell transplantation (HCT) markedly affects the lung microbiome corresponding with a high incidence of post-HCT pulmonary complications. In a preclinical mouse model of HCT, we observed a reduction in Lactobacillus johnsonii within the lung microbiome following transplantation. Intranasal administration of live or heat-killed (HK) L. johnsonii at low doses reduced gammaherpesvirus-induced pulmonary fibrosis in HCT mice, in which IL-17A plays an essential role. HK L. johnsonii treatment of HCT mice suppressed inflammatory cytokine production by lung macrophages and decreased Il17a expression in T helper 17 (Th17) cells. HK L. johnsonii increased PD-L1 expression on the surface of type II conventional dendritic cells (cDC2) in HCT mice and in vitro in bone marrow-derived dendritic cells (BMDCs). HK L. johnsonii-exposed BMDCs also inhibited IL-17A secretion from co-cultured Th17 cells in a PD-1-dependent manner. Notably, when HK L. johnsonii was administered to HCT mice reconstituted with bone marrow cells from PD-1 knockout (KO) mice, which lack a PD-L1 mediated response, HK L. johnsonii-mediated reduction of pulmonary fibrosis was negated. Collectively, our findings demonstrate that HK L. johnsonii mitigates herpesvirus-induced pulmonary fibrosis in HCT mice by modulating cDC2 surface expression of PD-L1, which subsequently suppresses Il17a expression in Th17 cells, pointing towards a potential postbiotic-based strategy for immunomodulation to address pulmonary complications of HCT.

immunology↗

bioRxiv2024

Dendritic Cell - Fibroblast Crosstalk via TLR9 and AHR Signaling Drives Lung Fibrogenesis

Idiopathic pulmonary fibrosis (IPF) is characterized by progressive scarring and loss of lung function. With limited treatment options, patients succumb to the disease within 2-5 years. The molecular pathogenesis of IPF regarding the immunologic changes that occur is poorly understood. We characterize a role for non-canonical aryl-hydrocarbon receptor signaling (ncAHR) in dendritic cells (DCs) that leads to production of IL-6 and IL-17, promoting fibrosis. TLR9 signaling in myofibroblasts is shown to regulate production of TDO2 which converts tryptophan into the endogenous AHR ligand kynurenine. Mice with augmented ncAHR signaling were created by crossing floxed AHR exon-2 deletion mice (AHR{Delta}ex2) with mice harboring a CD11c-Cre. Bleomycin was used to study fibrotic pathogenesis. Isolated CD11c+ cells and primary fibroblasts were treated ex-vivo with relevant TLR agonists and AHR modulating compounds to study how AHR signaling influenced inflammatory cytokine production. Human datasets were also interrogated. Inhibition of all AHR signaling rescued fibrosis, however, AHR{Delta}ex2 mice treated with bleomycin developed more fibrosis and DCs from these mice were hyperinflammatory and profibrotic upon adoptive transfer. Treatment of fibrotic fibroblasts with TLR9 agonist increased expression of TDO2. Study of human samples corroborate the relevance of these findings in IPF patients. We also, for the first time, identify that AHR exon-2 floxed mice retain capacity for ncAHR signaling.

immunology↗

bioRxiv2024

Cellular heterogeneity and dynamics of the human uterus in healthy premenopausal women

The human uterus is a complex and dynamic organ whose lining grows, remodels, and regenerates in every menstrual cycle or upon tissue damage. Here we applied single-cell RNA sequencing to profile more the 50,000 uterine cells from both the endometrium and myometrium of 5 healthy premenopausal individuals, and jointly analyzed the data with a previously published dataset from 15 subjects. The resulting normal uterus cell atlas contains more than 167K cells representing the lymphatic endothelium, blood endothelium, stromal, ciliated epithelium, unciliated epithelium, and immune cell populations. Focused analyses within each major cell type and comparisons with subtype labels from prior studies allowed us to document supporting evidence, resolve naming conflicts, and to propose a consensus annotation system of 39 subtypes. We release their gene expression centroids, differentially expressed genes, and mRNA patterns of literature-based markers as a shared community resource. We find many subtypes show dynamic changes over different phases of the cycle and identify multiple potential progenitor cells: compartment-wide progenitors for each major cell type, transitional cells that are upstream of other subtypes, and potential cross-lineage multipotent stromal progenitors that may be capable of replenishing the epithelial, stromal, and endothelial compartments. When compared to the healthy premenopausal samples, a postpartum and a postmenopausal uterus sample revealed substantially altered tissue composition, involving the rise or fall of stromal, endothelial, and immune cells. The cell taxonomy and molecular markers we report here are expected to inform studies of both basic biology of uterine function and its disorders. SIGNIFICANCEWe present single-cell RNA sequencing data from seven individuals (five healthy pre-menopausal women, one post-menopausal woman, and one postpartum) and perform an integrated analysis of this data alongside 15 previously published scRNA-seq datasets. We identified 39 distinct cell subtypes across four major cell types in the uterus. By using RNA velocity analysis and centroid-centroid comparisons we identify multiple computationally predicted progenitor populations for each of the major cell compartments, as well as potential cross-compartment, multi-potent progenitors. While the function and interactions of these cell populations remain to be validated through future experiments, the markers and their "dual characteristics" that we describe will serve as a rich resource to the scientific community. Importantly, we address a significant challenge in the field: reconciling multiple uterine cell taxonomies being proposed. To achieve this, we focused on integrating historical and contemporary knowledge across multiple studies. By providing detailed evidence used for cell classification we lay the groundwork for establishing a stable, consensus cell atlas of the human uterus.

cell biology↗

bioRxiv2022

The ADP-heptose biosynthesis enzyme GmhB is a conserved Gram-negative bacteremia fitness factor

Klebsiella pneumoniae is a leading cause of Gram-negative bacteremia, which is a major source of morbidity and mortality worldwide. Gram-negative bacteremia requires three major steps: primary site infection, dissemination to the blood, and bloodstream survival. Since K. pneumoniae is a leading cause of healthcare-associated pneumonia, the lung is a common primary infection site leading to secondary bacteremia. K. pneumoniae factors essential for lung fitness have been characterized, but those required for subsequent bloodstream infection are unclear. To identify K. pneumoniae genes associated with dissemination and bloodstream survival, we performed insertion site sequencing (InSeq) using a pool of >25,000 transposon mutants in a murine model of bacteremic pneumonia. This analysis revealed the gene gmhB as important for either dissemination from the lung or bloodstream survival. In Escherichia coli, GmhB is a partially redundant enzyme in the synthesis of ADP-heptose for the lipopolysaccharide (LPS) core. To characterize its function in K. pneumoniae, an isogenic knockout strain ({Delta}gmhB) and complemented mutant were generated. During pneumonia, GmhB did not contribute to lung fitness and did not alter normal immune responses. However, GmhB enhanced bloodstream survival in a manner independent of serum susceptibility, specifically conveying resistance to spleen-mediated killing. In a tail-vein injection of murine bacteremia, GmhB was also required by K. pneumoniae, E. coli and Citrobacter freundii for optimal bloodstream survival. Together, this study identifies GmhB as a conserved Gram-negative bacteremia fitness factor that acts through LPS-mediated mechanisms to enhance bloodstream survival. IMPORTANCEKlebsiella pneumoniae frequently causes healthcare-associated infections including pneumonia and bacteremia. This is particularly concerning due to emerging antimicrobial resistance and the propensity for bacteremia to initiate sepsis, which has high mortality and is the most expensive hospital-treated condition. Defining mechanisms of bloodstream survival is critical to understanding the pathology of bacteremia and identifying novel targets for future therapies. In this study, we identified the K. pneumoniae enzyme GmhB as a bloodstream-specific fitness factor that enables the bacteria to survive in the spleen but is dispensable in the lung. Furthermore, GmhB is also needed by the related bacterial pathogens Escherichia coli and Citrobacter freundii to cause bacteremia. Conserved bacteremia fitness factors such a GmhB could be the basis for future therapeutics that would alleviate significant disease caused by from multiple diverse pathogens.

microbiology↗