Biology subjects

Weiner, A. I.

Publications and source records attributed to Weiner, A. I..

6 recordsLinked to original sources

bioRxiv2026

A Bioactive Phospholipid Promotes Rapid Progenitor Lung Progenitor Activation via AP-1

Upon injury to the distal lung, alveolar type 2 cells (AT2s) must make a discrete switch from surfactant factories to stem cells capable of regeneration, which involves both proliferation and differentiation into oxygen-exchanging alveolar type 1 (AT1) cells. However, the discrete signals and molecular pathways facilitating this fundamental switch in AT2 functionality are uncertain. Here we demonstrate that the bioactive lipid lysophosphatidic acid (LPA), typically associated with driving fibrosis, is an extremely efficient inducer of this state change in comparison to previously implicated signals IL-1{beta} and p53 stabilization. We observed endogenous production and accumulation of LPA in influenza-injured murine lungs, creating a microenvironment that facilitates AT2 progenitor switching. Multiple transcriptomic approaches reveal elevation of Fosl1 and Jun, core members of the Activator Protein 1 (AP-1) transcription factor family, in response to LPA. Using novel genetic models combined with influenza injury, we demonstrate that AP-1 activity in AT2s is necessary for effective alveolar regeneration at both the cellular and physiologic levels. These findings unveil a critical relationship between paracrine LPA and cell-intrinsic AP-1 in facilitating effective lung alveolar regeneration. HighlightsO_LILPA facilitates progenitor switching in lung regeneration via initiation of a discrete transcriptomic state C_LIO_LILPA promotes AT2 state switching via Jun (AP-1) C_LIO_LIImpaired AP-1 signaling significantly restricts recovery from influenza infection C_LI

cell biology↗

bioRxiv2024

Disruption of Immune Responses By Type I Diabetes Exacerbates SARS-CoV-2 Mediated Lung Injury

COVID-19 commonly presents as pneumonia, with those most severely affected progressing to respiratory failure. Patient responses to SARS-CoV-2 infection are varied, with comorbidities acting as major contributors to varied outcomes. Focusing on one such major comorbidity, we assessed whether pharmacological induction of Type I Diabetes Mellitus (T1DM) would increase the severity of lung injury in a murine model of COVID-19 pneumonia utilizing wild type mice infected with mouse-adapted SARS-CoV-2. Hyperglycemic mice exhibited increased weight loss and reduced blood oxygen saturation in comparison to their euglycemic counterparts, suggesting that these animals indeed experienced more severe lung injury. Transcriptomic analysis revealed a significant impairment of the adaptive immune response in the lungs of diabetic mice compared to those of control. In order to expand the limited options available for tissue analysis due to biosafety restrictions, we also employed a novel technique to digest highly fixed tissue into a single cell suspension, which allowed for flow cytometric analysis as well as single cell RNA sequencing. Flow immunophenotyping and scRNA-Seq confirmed impaired recruitment of T cells into the lungs of T1DM animals. Additionally, scRNA-Seq revealed a distinct, highly inflammatory macrophage profile in the diabetic cohort that correlates with the more severe infection these mice experienced clinically, allowing insight into a possible mechanism for this phenomenon. Recognizing the near certainty that respiratory viruses will continue to present significant public health concerns for the foreseeable future, our study provides key insights into how T1DM results in a much more severe infection and identifies possible targets to ameliorate comorbidity-associated severe disease. NEW AND NOTEWORTHYWe define the exacerbating effects of Type I Diabetes Mellitus (T1DM) on COVID-19 pneumonia severity in mice. Hyperglycemic mice experienced increased weight loss and reduced oxygen saturation. Transcriptomic analysis revealed impaired immune responses in diabetic mice, while flow cytometry and single-cell RNA sequencing confirmed reduced T cell recruitment and an inflammatory macrophage profile. Additionally, we introduced a novel technique for tissue analysis, enabling flow cytometric analysis and single-cell RNA sequencing on highly fixed tissue samples.

immunology↗

bioRxiv2024

Impaired AMPK Control of Alveolar Epithelial Cell Metabolism Promotes Pulmonary Fibrosis

Alveolar epithelial type II (AT2) cell dysfunction is implicated in the pathogenesis of familial and sporadic idiopathic pulmonary fibrosis (IPF). We previously described that expression of an AT2 cell exclusive disease-associated protein isoform (SP-CI73T) in murine and patient-specific induced pluripotent stem cell (iPSC)-derived AT2 cells leads to a block in late macroautophagy and promotes time-dependent mitochondrial impairments; however, how a metabolically dysfunctional AT2 cell results in fibrosis remains elusive. Here using murine and human iPSC-derived AT2 cell models expressing SP-CI73T, we characterize the molecular mechanisms governing alterations in AT2 cell metabolism that lead to increased glycolysis, decreased mitochondrial biogenesis, disrupted fatty acid oxidation, accumulation of impaired mitochondria, and diminished AT2 cell progenitor capacity manifesting as reduced AT2 self-renewal and accumulation of transitional epithelial cells. We identify deficient AMP-kinase signaling as a key upstream signaling hub driving disease in these dysfunctional AT2 cells and augment this pathway to restore alveolar epithelial metabolic function, thus successfully alleviating lung fibrosis in vivo.

molecular biology↗

bioRxiv2023

Vascular Endothelial-derived SPARCL1 Exacerbates Viral Pneumonia Through Pro-Inflammatory Macrophage Activation

Inflammation upon infectious lung injury is a double-edged sword: while tissue-infiltrating immune cells and cytokines are necessary to control infection, these same factors often aggravate injury. Full appreciation of both the sources and targets of inflammatory mediators is required to facilitate strategies to maintain antimicrobial effects while minimizing off-target epithelial and endothelial damage. Recognizing that the vasculature is centrally involved in tissue responses to injury and infection, we observed that pulmonary capillary endothelial cells (ECs) exhibit dramatic transcriptomic changes upon influenza injury punctuated by profound upregulation of Sparcl1. Endothelial deletion and overexpression of SPARCL1 implicated this secreted matricellular protein in driving key pathophysiologic symptoms of pneumonia, which we demonstrate result from its effects on macrophage polarization. SPARCL1 induces a shift to a pro-inflammatory "M1-like" phenotype (CD86+CD206-), thereby increasing associated cytokine levels. Mechanistically, SPARCL1 acts directly on macrophages in vitro to induce the pro-inflammatory phenotype via activation of TLR4, and TLR4 inhibition in vivo ameliorates inflammatory exacerbations caused by endothelial Sparcl1 overexpression. Finally, we confirmed significant elevation of SPARCL1 in COVID-19 lung ECs in comparison with those from healthy donors. Survival analysis demonstrated that patients with fatal COVID-19 had higher levels of circulating SPARCL1 protein compared to those who recovered, indicating the potential of SPARCL1 as a biomarker for prognosis of pneumonia and suggesting that personalized medicine approaches might be harnessed to block SPARCL1 and improve outcomes in high-expressing patients.

immunology↗

bioRxiv2022

ΔNp63 drives dysplastic alveolar remodeling and restricts epithelial plasticity upon severe lung injury

Unlike many mammalian vital organs, the lung exhibits a robust, multifaceted regenerative response to severe injuries such as influenza infection, which primarily targets epithelial cells in the airways and alveoli. Quiescent lung-resident epithelial progenitors proliferate, migrate, and differentiate following lung injury, participating in two distinct reparative pathways: functionally beneficial regeneration and dysplastic tissue remodeling. Intrapulmonary airway-resident basal-like p63+ progenitors are one such progenitor cell type that migrates from the airways to form ectopic bronchiolar tissue in the alveoli, generating honeycomb-like cysts that fail to resolve after injury. Though this phenomenon is now well described, the cell-autonomous signals that drive dysplastic alveolar remodeling remain uncertain, a question made especially salient by observations that p63+ progenitors also expand dramatically upon diffuse alveolar damage in humans resulting from a variety of insults including SARS-CoV-2-induced ARDS. Here we show that the master basal cell transcription factor {Delta}Np63 is required for the immense migratory capacity of intrapulmonary p63+ progenitors and consequently for the dysplastic repair pathway manifest by these cells. We further demonstrate that {Delta}Np63 restricts the fate plasticity of intrapulmonary p63+ progenitors by regulating their epigenetic landscape, and that loss of {Delta}Np63 alters the deposition of active and repressive histone modifications at key differentiation gene loci, allowing {Delta}Np63KO progenitors to proceed towards airway or alveolar differentiation depending on their surrounding environment. These insights into the regulatory mechanisms of dysplastic repair and intrapulmonary p63+ progenitor fate choice highlight potential therapeutic targets to promote more effective alveolar regeneration following severe lung injuries.

molecular biology↗

bioRxiv2020

Orthotopic Transplantation and Engraftment of Human Induced Pluripotent Stem Cell-Derived Alveolar Progenitor Cells into Murine Lungs

Humanized mice possessing human cells, tissues, or organ systems provide an unparalleled platform for preclinical studies in oncology, immunology, and infectious diseases. While the lungs are a vital organ subject to a wide variety of pathologies, exemplified by the ongoing COVID-19 pandemic, discrete differences in murine and human lungs can obfuscate interpretation of murine models of lung disease. Here we provide proof-of-concept methodology for the potential humanization of murine lungs via orthotopic transplantation of human NKX2.1+ progenitor cells and alveolar type 2 cells derived from induced pluripotent stem cells. We show that these cells engraft readily into highly immunocompromised mice after pharmacological injury with bleomycin, which presumably generates "space" for human cells to access denuded basement membrane and engraft. Transplanted cells stably retain their pulmonary lineage restriction and persist as superficially differentiated alveolar type 2 and type 1 cells. Future work should focus on strategies to promote xenorepopulation of most / all of the murine lung with human cells while retaining appropriate regio-specific epithelial differentiation and normal physiological function.

developmental biology↗