8 research outputs found
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IFNγ-Dependent Tissue-Immune Homeostasis Is Co-opted in the Tumor Microenvironment
Homeostatic programs balance immune protection and self-tolerance. Such mechanisms likely impact autoimmunity and tumor formation, respectively. How homeostasis is maintained and impacts tumor surveillance is unknown. Here, we find that different immune mononuclear phagocytes share a conserved steady-state program during differentiation and entry into healthy tissue. IFNγ is necessary and sufficient to induce this program, revealing a key instructive role. Remarkably, homeostatic and IFNγ-dependent programs enrich across primary human tumors, including melanoma, and stratify survival. Single-cell RNA sequencing (RNA-seq) reveals enrichment of homeostatic modules in monocytes and DCs from human metastatic melanoma. Suppressor-of-cytokine-2 (SOCS2) protein, a conserved program transcript, is expressed by mononuclear phagocytes infiltrating primary melanoma and is induced by IFNγ. SOCS2 limits adaptive anti-tumoral immunity and DC-based priming of T cells in vivo, indicating a critical regulatory role. These findings link immune homeostasis to key determinants of anti-tumoral immunity and escape, revealing co-opting of tissue-specific immune development in the tumor microenvironment. Keywords: dendritic cells; homeostasis; differentiation; IFNγ; tumor microenvironment; melanoma tolerance; immunotherapy; suppressor-of-cytokine-signaling 2 (SOCS2); tissue mononuclear phagocyte
SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.
There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection
Theoretical and Experimental Investigation of Thermodynamics and Kinetics of Thiol-Michael Addition Reactions: A Case Study of Reversible Fluorescent Probes for Glutathione Imaging in Single Cells
Theoretical and Experimental Investigation of Thermodynamics and Kinetics of Thiol-Michael Addition Reactions: A Case Study of Reversible Fluorescent Probes for Glutathione Imaging in Single Cells
Density
functional theory (DFT) was applied to study the thermodynamics
and kinetics of reversible thiol-Michael addition reactions. M06-2X/6-31G(d)
with the SMD solvation model can reliably predict the Gibbs free energy
changes (Δ<i>G</i>) of thiol-Michael addition reactions
with an error of less than 1 kcal·mol<sup>–1</sup> compared
with the experimental benchmarks. Taking advantage of this computational
model, the first reversible reaction-based fluorescent probe was developed
that can monitor the changes in glutathione levels in single living
cells
Quantitative Imaging of Glutathione in Live Cells Using a Reversible Reaction-Based Ratiometric Fluorescent Probe
Glutathione
(GSH) plays an important role in maintaining redox
homeostasis inside cells. Currently, there are no methods available
to quantitatively assess the GSH concentration in live cells. Live
cell fluorescence imaging revolutionized the field of cell biology
and has become an indispensable tool in current biological studies.
In order to minimize the disturbance to the biological system in live
cell imaging, the probe concentration needs to be significantly lower
than the analyte concentration. Because of this, any irreversible
reaction-based GSH probe can only provide qualitative results within
a short reaction time and will exhibit maximum response regardless
of the GSH concentration if the reaction is completed. A reversible
reaction-based probe with an appropriate equilibrium constant allows
measurement of an analyte at much higher concentrations and, thus,
is a prerequisite for GSH quantification inside cells. In this contribution,
we report the first fluorescent probeThiolQuant Green (TQ
Green)for quantitative imaging of GSH in live cells. Due to
the reversible nature of the reaction between the probe and GSH, we
are able to quantify mM concentrations of GSH with TQ Green concentrations
as low as 20 nM. Furthermore, the GSH concentrations measured using
TQ Green in 3T3-L1, HeLa, HepG2, PANC-1, and PANC-28 cells are reproducible
and well correlated with the values obtained from cell lysates. TQ
Green imaging can also resolve the changes in GSH concentration in
PANC-1 cells upon diethylmaleate (DEM) treatment. In addition, TQ
Green can be conveniently applied in fluorescence activated cell sorting
(FACS) to measure GSH level changes. Through this study, we not only
demonstrate the importance of reaction reversibility in designing
quantitative reaction-based fluorescent probes but also provide a
practical tool to facilitate redox biology studies
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SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.
There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection