Hyaluronan Directs Alveolar Type II Cell Response to Acute Ozone Exposure in Mice.

Becoming more frequent due to climate change, ozone (O) exposures can cause lung injury. Alveolar type 2 (AT2) cells and hyaluronan (HA), a matrix component, are critical to repairing lung injury and restoring homeostasis. Here, we define the impact of HA on AT2 cells following acute O exposure.

Influenza B virus infection alters the regenerative potential of murine alveolar type 2 pneumocytes.

Unlabelled: Respiratory epithelial cells can survive direct infection by influenza viruses, and the long-term consequences of that infection have been characterized in a subset of proximal airway cell types. The impact on the cells that survive viral infection in the distal lung epithelia, however, is much less well-characterized. Utilizing a Cre-expressing influenza B virus (IBV) and a lox-stop-lox tdTomato reporter mouse model, we identified that alveolar type 2 (AT2) pneumocytes, a progenitor cell type in the distal lung, can survive viral infection.

Topology-Driven Discovery of Transmembrane Protein -Palmitoylation.

Protein -palmitoylation is a reversible lipophilic posttranslational modification regulating a diverse number of signaling pathways. Within transmembrane proteins (TMPs), -palmitoylation is implicated in conditions from inflammatory disorders to respiratory viral infections. Many small-scale experiments have observed -palmitoylation at juxtamembrane Cys residues.

Analysis of Protein Cysteine Acylation Using a Modified Suspension Trap (Acyl-Trap).

Proteins undergo reversible -acylation via a thioester linkage in vivo. -palmitoylation, modification by C16:0 fatty acid, is a common -acylation that mediates critical protein-membrane and protein-protein interactions. The most widely used -acylation assays, including acyl-biotin exchange and acyl resin-assisted capture, utilize blocking of free Cys thiols, hydroxylamine-dependent cleavage of the thioester and subsequent labeling of nascent thiol.

Altered ontogeny and transcriptomic signatures of tissue-resident pulmonary interstitial macrophages ameliorate allergic airway hyperresponsiveness.

Introduction: Environmental exposures and experimental manipulations can alter the ontogenetic composition of tissue-resident macrophages. However, the impact of these alterations on subsequent immune responses, particularly in allergic airway diseases, remains poorly understood. This study aims to elucidate the significance of modified macrophage ontogeny resulting from environmental exposures on allergic airway responses to house dust mite (HDM) allergen.

SARS-CoV-2 variant of concern fitness and adaptation in primary human airway epithelia.

The severe acute respiratory syndrome coronavirus 2 pandemic is characterized by the emergence of novel variants of concern (VOCs) that replace ancestral strains. Here, we dissect the complex selective pressures by evaluating variant fitness and adaptation in human respiratory tissues. We evaluate viral properties and host responses to reconstruct forces behind D614G through Omicron (BA.

Analysis of Protein Cysteine Acylation Using a Modified Suspension Trap (Acyl-Trap).

Proteins undergo reversible -acylation via a thioester linkage in vivo. -palmitoylation, modification by C16:0 fatty acid, is a common -acylation that mediates critical protein-membrane and protein-protein interactions. The most widely used -acylation assays, including acyl-biotin exchange and acyl resin-assisted capture, utilize blocking of free Cys thiols, hydroxylamine-dependent cleavage of the thioester and subsequent labeling of nascent thiol.

Stem cell migration drives lung repair in living mice.

Tissue repair requires a highly coordinated cellular response to injury. In the lung, alveolar type 2 cells (AT2s) act as stem cells to replenish both themselves and alveolar type 1 cells (AT1s); however, the complex orchestration of stem cell activity after injury is poorly understood. Here, we establish longitudinal imaging of AT2s in murine intact tissues ex vivo and in vivo in order to track their dynamic behavior over time.

Recent advances in lung organoid development and applications in disease modeling.

Over the last decade, several organoid models have evolved to acquire increasing cellular, structural, and functional complexity. Advanced lung organoid platforms derived from various sources, including adult, fetal, and induced pluripotent stem cells, have now been generated, which more closely mimic the cellular architecture found within the airways and alveoli. In this regard, the establishment of novel protocols with optimized stem cell isolation and culture conditions has given rise to an array of models able to study key cellular and molecular players involved in lung injury and repair.

Transitional cell states sculpt tissue topology during lung regeneration.

Organ regeneration requires dynamic cell interactions to reestablish cell numbers and tissue architecture. While we know the identity of progenitor cells that replace lost tissue, the transient states they give rise to and their role in repair remain elusive. Here, using multiple injury models, we find that alveolar fibroblasts acquire distinct states marked by Sfrp1 and Runx1 that influence tissue remodeling and reorganization.

Host range, transmissibility and antigenicity of a pangolin coronavirus.

The pathogenic and cross-species transmission potential of SARS-CoV-2-related coronaviruses (CoVs) remain poorly characterized. Here we recovered a wild-type pangolin (Pg) CoV GD strain including derivatives encoding reporter genes using reverse genetics. In primary human cells, PgCoV replicated efficiently but with reduced fitness and showed less efficient transmission via airborne route compared with SARS-CoV-2 in hamsters.

Meta-Analysis of COVID-19 BAL Single-Cell RNA Sequencing Reveals Alveolar Epithelial Transitions and Unique Alveolar Epithelial Cell Fates.

Single-cell RNA sequencing (scRNA-seq) of BAL cells has provided insights into coronavirus disease (COVID-19). However, reports have been limited by small patient cohorts. We performed a meta-analysis of BAL scRNA-seq data from healthy control subjects ( = 13) and patients with COVID-19 ( = 20), sourced from six independent studies (167,280 high-quality cells in total).

GAA deficiency disrupts distal airway cells in Pompe disease.

Pompe disease is an autosomal recessive glycogen storage disease caused by mutations in the gene that encodes acid alpha-glucosidase (GAA)-an enzyme responsible for hydrolyzing lysosomal glycogen. GAA deficiency results in systemic lysosomal glycogen accumulation and cellular disruption. Glycogen accumulation in skeletal muscles, motor neurons, and airway smooth muscle cells is known to contribute to respiratory insufficiency in Pompe disease.

Efficient Adeno-associated Virus-mediated Transgenesis in Alveolar Stem Cells and Associated Niches.

Targeted delivery of transgenes to tissue-resident stem cells and related niches offers avenues for interrogating pathways and editing endogenous alleles for therapeutic interventions. Here, we survey multiple adeno-associated virus (AAV) serotypes, administered via intranasal and retroorbital routes in mice, to target lung alveolar stem cell niches. We found that AAV5, AAV4, and AAV8 efficiently and preferentially transduce alveolar type-2 stem cells (AT2s), endothelial cells, and PDGFRA fibroblasts, respectively.

An integrated cell atlas of the lung in health and disease.

Single-cell technologies have transformed our understanding of human tissues. Yet, studies typically capture only a limited number of donors and disagree on cell type definitions. Integrating many single-cell datasets can address these limitations of individual studies and capture the variability present in the population.

Regionally distinct progenitor cells in the lower airway give rise to neuroendocrine and multiciliated cells in the developing human lung.

Using scRNA-seq and microscopy, we describe a cell that is enriched in the lower airways of the developing human lung and identified by the unique coexpression of . To functionally interrogate these cells, we apply a single-cell barcode-based lineage tracing method, called CellTagging, to track the fate of cells during airway organoid differentiation in vitro. Lineage tracing reveals that these cells have a distinct differentiation potential from basal cells, giving rise predominantly to pulmonary neuroendocrine cells and a subset of multiciliated cells distinguished by high and low expression.

Allergic Asthma Responses Are Dependent on Macrophage Ontogeny.

The ontogenetic composition of tissue-resident macrophages following injury, environmental exposure, or experimental depletion can be altered upon re-establishment of homeostasis. However, the impact of altered resident macrophage ontogenetic milieu on subsequent immune responses is poorly understood. Hence, we assessed the effect of macrophage ontogeny alteration following return to homeostasis on subsequent allergic airway responses to house dust mites (HDM).

Sex differences in resilience to ferroptosis underlie sexual dimorphism in kidney injury and repair.

In both humans and mice, repair of acute kidney injury is worse in males than in females. Here, we provide evidence that this sexual dimorphism results from sex differences in ferroptosis, an iron-dependent, lipid-peroxidation-driven regulated cell death. Using genetic and single-cell transcriptomic approaches in mice, we report that female sex confers striking protection against ferroptosis, which was experimentally induced in proximal tubular (PT) cells by deleting glutathione peroxidase 4 (Gpx4).

Host protein kinases required for SARS-CoV-2 nucleocapsid phosphorylation and viral replication.

Multiple coronaviruses have emerged independently in the past 20 years that cause lethal human diseases. Although vaccine development targeting these viruses has been accelerated substantially, there remain patients requiring treatment who cannot be vaccinated or who experience breakthrough infections. Understanding the common host factors necessary for the life cycles of coronaviruses may reveal conserved therapeutic targets.

Multi-apical polarity of alveolar stem cells and their dynamics during lung development and regeneration.

Epithelial cells of diverse tissues are characterized by the presence of a single apical domain. In the lung, electron microscopy studies have suggested that alveolar type-2 epithelial cells (AT2s) en face multiple alveolar sacs. However, apical and basolateral organization of the AT2s and their establishment during development and remodeling after injury repair remain unknown.

Coupled myovascular expansion directs cardiac growth and regeneration.

Heart regeneration requires multiple cell types to enable cardiomyocyte (CM) proliferation. How these cells interact to create growth niches is unclear. Here, we profile proliferation kinetics of cardiac endothelial cells (CECs) and CMs in the neonatal mouse heart and find that they are spatiotemporally coupled.

Defined conditions for long-term expansion of murine and human alveolar epithelial stem cells in three-dimensional cultures.

Alveolar type 2 cells (AT2s) serve as stem cells of the alveoli and restore cell numbers after injury. Here, we describe a detailed protocol for the isolation, purification, and culture of murine and human AT2s. We have developed chemically defined and stroma-free culture conditions that enable expansion and maintenance of AT2s.