Schlapbach, C. | Search bioRxiv

bioRxiv2022

PPAR-γ regulates the effector function of human TH9 cells by promoting glycolysis

T helper 9 cells (TH9) are key drivers of allergic tissue inflammation. They are characterized by the expression of type 2 cytokines, such as IL-9 and IL-13, and the peroxisome proliferator-activated receptor gamma (PPAR-{gamma}) transcription factor. However, the functional role of PPAR-{gamma} in human TH9 cells remains unknown. Here, we demonstrate that PPAR-{gamma} drives activation-induced glycolysis, which, in turn, specifically promotes the expression of IL-9, but not IL-13, in an mTORC1-dependent manner. In vitro and ex vivo experiments on skin samples of allergic contact dermatitis showed that the PPAR-{gamma}-mTORC1-IL-9 pathway was active in TH9 cells in human skin inflammation. Additionally, we found that tissue glucose levels were dynamically regulated in acute allergic skin inflammation, suggesting that in situ glucose availability is linked to distinct immunological signals in vivo. Furthermore, paracrine IL-9 induced the lactate transporter MCT1 in IL-9R+ TH cells, where it increased aerobic glycolysis and proliferative capacity. Taken together, our findings delineate a hitherto unknown relationship between PPAR-{gamma}-dependent glucose metabolism and the pathogenic effector function of human TH9 cells. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=84 SRC="FIGDIR/small/503972v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@ce684borg.highwire.dtl.DTLVardef@12121acorg.highwire.dtl.DTLVardef@29d712org.highwire.dtl.DTLVardef@e71117_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2019

Salivary gland macrophages assist tissue-resident CD8+ T cell immune surveillance

Tissue macrophages and tissue resident memory CD8+ T cells (TRM) play important roles for pathogen sensing and rapid protection of barrier tissues. To date, it is incompletely understood how these two cell types cooperate for efficient organ surveillance during homeostasis. Here, we used intravital imaging to show that TRM dynamically crawled along tissue macrophages in murine submandibular salivary glands (SMG) during the memory phase following a viral infection. Ex vivo confined SMG TRM integrated an unexpectedly wide range of migration modes: in addition to chemokine-and adhesion receptor-driven motility, SMG TRM displayed a remarkable capacity of autonomous motility in the absence of chemoattractants and adhesive ligands. This unique intrinsic SMG TRM motility was transmitted by friction and adaptation to microenvironmental topography through protrusion insertion into permissive gaps. Analysis of extracellular space in SMG using super-resolution shadow imaging showed discontinuous attachment of tissue macrophages to neighboring epithelial cells, offering paths of least resistance for patrolling TRM. Upon tissue macrophage depletion, intraepithelial SMG TRM showed decreased motility and reduced epithelial crossing events, and failed to cluster in response to local inflammatory chemokine stimuli. In sum, our data uncover a continuum of SMG TRM migration modes and identify a new accessory function of tissue macrophages to facilitate TRM patrolling of the complex exocrine gland architecture.\n\nOne sentence summaryCombined in vitro and in vivo imaging of salivary gland-resident tissue memory CD8+ T cells (TRM) uncovers their unique migratory behavior and describes a novel accessory function of tissue macrophages to assist TRM surveillance.

immunology↗