Biology subjects

Thistlethwaite, P. A.

Publications and source records attributed to Thistlethwaite, P. A..

3 recordsLinked to original sources

bioRxiv2026

An Endocytic Checkpoint Controls Macrophage PD-1 Function and Immunotherapy Fate

Responses to PD1 blockade span durable tumor control to hyperprogressive disease (HPD), yet innate immune mechanisms governing these extremes remain undefined. Here we integrate a macrophage systems atlas (>12,500 transcriptomes) with single-cell profiles from >1,000 anti-PD1 treated patients, to identify CCDC88A (GIV) as a macrophage-intrinsic determinant of durable response versus HPD. GIV loss increases PD1 surface retention, suppresses phagocytosis, and accelerates tumor growth across murine models, human macrophages, and patient-derived organoids. Myeloid-specific GIV deletion converts PD1 blockade from tumor-restraining to tumor-accelerating by reprogramming macrophages toward HPD-like states. Mechanistically, GIV engages a conserved TIR-like [TILL] motif within the PD1 cytoplasmic tail to drive dynamin-dependent endocytosis, coupling innate immune signaling logic to checkpoint receptor trafficking. Pharmacologic disruption of this axis phenocopies GIV loss, revealing an endocytic vulnerability that undermines checkpoint efficacy and triggers accelerated growth at relapse. These findings define PD1 routing, rather than ligand-binding, as a macrophage-encoded checkpoint governing antitumor immunity. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/718292v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@a8f83aorg.highwire.dtl.DTLVardef@140dc7dorg.highwire.dtl.DTLVardef@14bc366org.highwire.dtl.DTLVardef@1096b8a_HPS_FORMAT_FIGEXP M_FIG GRAPHIC ABSTRACT C_FIG In briefMullick et al. show that PD1 trafficking in tumor associated macrophages (TAMs), controlled by the endocytic adaptor GIV/Girdin, determines the durability of immunotherapy. Disrupting this pathway traps PD1 at the surface, converts checkpoint blockade into hyperprogressive disease, and abolishes therapeutic benefit, revealing PD1 routing as a macrophage-encoded checkpoint of immunotherapy outcome. HighlightsO_LIGIV defines macrophage states that stratify durable response vs hyperprogressive disease C_LIO_LIGIV limits surface checkpoint accumulation by facilitating PD1 endocytosis C_LIO_LILoss of GIV traps PD1 at the membrane and drives hyperprogressive disease C_LIO_LIEndocytic blockade phenocopies GIV loss and abolishes checkpoint efficacy C_LIO_LIPsychotropic drugs disrupt PD1 trafficking and accelerate tumor growth C_LI

cancer biology↗

bioRxiv2024

Store-operated Ca2+ entry is involved in endothelium-to-mesenchymal transition in lung vascular endothelial cells

Endothelial-to-mesenchymal transition (EndMT) is a biological process that converts endothelial cells to mesenchymal cells with increased proliferative and migrative abilities. EndMT has been implicated in the development of pulmonary vascular remodeling in pulmonary arterial hypertension (PAH), a fatal and progressive lung vascular disease. Transforming growth factor {beta}1 (TGF-{beta}1), an inflammatory cytokine, is known to induce EndMT in many types of endothelial cells including lung vascular endothelial cells (LVEC). An increase in cytosolic free Ca2+ concentration ([Ca2+]cyt) is a major stimulus for cellular proliferation and phenotypic transition, but it is unknown whether Ca2+ signaling is involved in EndMT. In this study we tested the hypothesis that TGF-{beta}1-induced EndMT in human LVEC is Ca2+-dependent. Treatment of LVEC with TGF-{beta}1 for 5-7 days resulted in increase in SNAI1/2 expression, induction of EndMT, upregulation of STIM/Orai1 and enhancement of store-operated Ca2+ entry (SOCE). Removal (or chelation) of extracellular or intracellular Ca2+ with EGTA or BAPTA-AM respectively abolished EndMT in response to TGF-{beta}1. Moreover, EGTA diminished TGF-{beta}1-induced increase in SNAI in a dose-dependent manner. Knockdown of either STIM1 or Orai1 was sufficient to prevent TGF-{beta}-mediated increase in SNAI1/2 and EndMT, but did not rescue the continuous adherent junctions. Blockade of Orai1 channels by AnCoA4 inhibited TGF-{beta}-mediated EndMT and restored PECAM1-positive continuous adherent junctions. In conclusion, intracellular Ca2+ signaling plays a critical role in TGF-{beta}-associated EndMT through enhanced SOCE and STIM1-Orai1 interaction. Thus, targeting Ca2+ signaling pathways regulating EndMT may be a novel therapeutic approach to treat PAH and other forms of pre-capillary pulmonary hypertension. New & NoteworthyEndMT has been reported to contribute to the pathogenesis of PH. In this study we aimed to determine the role of Ca2+ signaling in the development of EndMT in human lung vascular endothelial cells. Our data suggest that TGF-{beta}1 requires store-operated Ca2+ entry through STIM1/Orai channels to induce SNAI-mediated EndMT. For the first time we demonstrated that TGF-{beta}1-induced EndMT is Ca2+-dependent event while inhibition of STIM1/Orai interaction attenuated EndMT in response to TGF-{beta}1.

cell biology↗

bioRxiv2020

Adult Stem Cell-derived Complete Lung Organoid Models Emulate Lung Disease in COVID-19

SARS-CoV-2, the virus responsible for COVID-19, causes widespread damage in the lungs in the setting of an overzealous immune response whose origin remains unclear. We present a scalable, propagable, personalized, cost-effective adult stem cell-derived human lung organoid model that is complete with both proximal and distal airway epithelia. Monolayers derived from adult lung organoids (ALOs), primary airway cells, or hiPSC-derived alveolar type-II (AT2) pneumocytes were infected with SARS-CoV-2 to create in vitro lung models of COVID-19. Infected ALO-monolayers best recapitulated the transcriptomic signatures in diverse cohorts of COVID-19 patient-derived respiratory samples. The airway (proximal) cells were critical for sustained viral infection, whereas distal alveolar differentiation (AT2[->]AT1) was critical for mounting the overzealous host immune response in fatal disease; ALO monolayers with well-mixed proximodistal airway components recapitulated both. Findings validate a human lung model of COVID-19, which can be immediately utilized to investigate COVID-19 pathogenesis and vet new therapies and vaccines. GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/344002v4_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1d1507aorg.highwire.dtl.DTLVardef@faa17forg.highwire.dtl.DTLVardef@80ceb1org.highwire.dtl.DTLVardef@81d61c_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIHuman lung organoids with mixed proximodistal epithelia are created C_LIO_LIProximal airway cells are critical for viral infectivity C_LIO_LIDistal alveolar cells are important for emulating host response C_LIO_LIBoth are required for the overzealous response in severe COVID-19 C_LI IN BRIEFAn integrated stem cell-based disease modeling and computational approach demonstrate how both proximal airway epithelium is critical for SARS-CoV-2 infectivity, but distal differentiation of alveolar pneumocytes is critical for simulating the overzealous host response in fatal COVID-19.

cell biology↗