Project description:Detailed knowledge about dynamics of SARS-CoV-2 infection in vivo is important for unraveling the viral and host response factors that contribute to COVID-19 pathogenesis. The unknown dose and exposure timing in human infections makes the needed well-controlled time course studies impossible and thus animal models of disease are essential to fill in the gaps in our understanding of disease progression. Old-World nonhuman primate species recapitulate mild COVID-19 cases, thereby serving as important models for studying disease pathogenesis. In this study, we compare African green monkeys (AGM; Chlorocebus sabaeus) inoculated with SARS-CoV-2 to AGM inoculated with a gamma-irradiated form of the virus to study the dynamics of virus replication throughout the respiratory tract and other target tissues. RNA sequencing of single cells from the lungs and mediastinal lymph nodes allowed a high-resolution, simultaneous analysis of virus replication and the host response in these tissues over time. Viral replication was mainly localized to the lower respiratory tract, especially the pneumocyte population. However, even in the absence of active replication, viral genomic RNA is was highly stable, especially in the upper respiratory tract. Macrophages play a vital and dynamic role in initiating a pro-inflammatory state in the lungs, while also interacting with infected pneumocytes. Together, our dataset provides a detailed view of changes in host and virus replication dynamics over the course of a mild COVID-19 infection and serves as a valuable resource to identify new therapeutic targets.
Project description:Exposure to cigarette smoke (CS) is etiologically linked to the development of fatal respiratory diseases, and there is a need to understand the mechanisms whereby CS causes damage. While animal models have provided valuable insights into smoking-related respiratory tract damage, modern toxicity testing calls for reliable in vitro models as alternatives for animal experimentation. Primary cells and immortalized cell lines can be used to gain some insight; however, the three-dimensional organotypic culture systems probably better mimic the morphological, physiological, and molecular attributes of the human respiratory tract. Even though the bronchus, bronchioles, and lung parenchyma are the primary sites of smoking-related respiratory disease manifestation, the nasal epithelium has been proposed as a surrogate tissue to study the effects of smoking on the respiratory tract. Here, we report on a repeated whole mainstream CS exposure of nasal and bronchial organotypic tissue cultures from which transcriptomic data were collected at several post-exposure time points. Despite the remarkably similar histology and cellular response to whole CS in both tissue types, as measured by cellular staining and cytokine secretion assessment, transcriptomic analyses combined with quantitative biological network modeling identified biological mechanisms that were unique to bronchial tissue at late post-exposure time points. Organotypic models therefore appear to be a promising alternative to animal experimentation, and provide species-relevant insights into the effects of CS exposure on the respiratory system.
Project description:Microgravity and space radiation (SR) are two highly influential factors affecting humans in space flight. Many health problems reported by astronauts derive from endothelial dysfunction and impaired homeostasis. Here we describe the adaptive response of human, capillary endothelial cells to space. Reference samples on ground and at 1g onboard allowed discrimination between the contribution of microgravity and SR within the combined response to space. Cell softening and reduced motility occurred in space, with loss of actin stress fibers and a greater distribution of microtubules and intermediate filaments in compensation. The frequency of primary cilia also increased. DNA repair mechanisms were indeed activated. Transcriptomics highlighted the opposing effect of microgravity from SR on specific molecular pathways: radiation, unlike microgravity, stimulated pathways for endothelial activation (hypoxia, inflammation), DNA repair and apoptosis, promoting an ageing-like phenotype; microgravity, unlike SR, activated pathways for metabolism and pro-proliferation phenotype. Thus, microgravity and SR should be considered separately to tailor effective countermeasures to protect astronauts’ health.
