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Biology subjects

Niaudet, C.

Publications and source records attributed to Niaudet, C..

3 recordsLinked to original sources

Functional diversity of Vγ9Vδ2 T cells overcomes glioblastoma state plasticity and antigen heterogeneity

Glioblastoma (GBM) is characterized by a high degree of cellular plasticity and intra-tumoral heterogeneity, which frequently leads to the failure of standard therapies, including immunotherapies. While chimeric antigen receptor (CAR) T cells offer a potent means of MHC-independent tumor recognition, their efficacy is hampered by the coexistence of distinct molecular states, gathered as proneural (PN) and mesenchymal (MES) phenotypes. Here, we demonstrate that gangliosides GD2 and O-acetylated GD2 (OAcGD2) are preferentially expressed by PN cells whereas MES cells display reduced expression due to upregulated ganglioside catabolism. Conversely, MES cells are known to exhibit high expression of stress-induced ligands recognized by V{gamma}9V{delta}2 T cells. We show that while engineering V{delta}2T cells with GD2- or OAcGD2-specific CAR enables the elimination of PN cells, it also facilitates the immune escape of MES cells in heterogeneous 3D-tumoroid models. Mechanistically, we reveal a hierarchy of receptor engagement, where CAR signaling predominates leading to the structural and functional exclusion of endogenous TCR from the immunological synapse. To address this receptor competition, we propose a strategy that leverages the functional effector diversity by combining untransduced and CAR-engineered V{delta}2T cells. This dual approach provides a dynamic safety net by ensuring the simultaneous elimination of PN and MES cells and preventing the selective outgrowth of resistant cells. Our findings establish a conceptual framework for designing off-the-shelf immunotherapies tailored to the metabolic and phenotypic plasticity of resistant solid tumors.

cancer biology↗

Therapeutic activation of endothelial sphingosine 1-phosphate receptor-1 by chaperone-bound S1P suppresses proliferative retinal vasculopathy

Sphingosine-1-phosphate (S1P), a bioactive lipid mediator that signals via G protein-coupled S1P receptors (S1PR), is required for normal vascular development. The role of this signaling axis in vascular retinopathies is largely unexplored. Here we show in a mouse model of oxygen-induced retinopathy (OIR) that endothelial overexpression of S1pr1 suppresses while endothelial knockout (KO) of S1pr1 worsens neovascular tuft formation. Furthermore, neovascular tufts are increased in Apom KO mice which lack HDL-bound S1P while they are suppressed in Apom TG mice which has more circulating HDL-S1P. These results suggest that circulating HDL-S1P activation of endothelial S1PR1 specifically suppresses proliferative retinal vasculopathy. Moreover, systemic administration of ApoM-Fc-bound S1P or a small molecule Gi-biased S1PR1 agonist suppressed neovascular tuft formation. Circulating HDL-S1P activation of endothelial S1PR1 may be a key protective mechanism to guard against neovascular retinopathies that occur not only in premature infants but also in diabetes and aging.

pathology↗

Endothelial-derived sphingolipids are required for vascular development and systemic lipid homeostasis

Serine palmitoyl transferase (SPT), the rate-limiting enzyme in the de novo synthesis of sphingolipids (SL), is needed for embryonic development, physiological homeostasis, and response to stress. The functions of de novo SL synthesis in vascular endothelial cells (EC), which line the entire circulatory system, are not well understood. Here we show that the EC de novo synthesis not only impacts vascular development but also maintains normal SL metabolic homeostasis in the circulatory system and peripheral organs. Mice with an endothelial-specific gene knockout of SPTLC1 (Sptlc1 ECKO), an essential subunit of the SPT complex, exhibited EC-intrinsic effects including reduced EC proliferation and tip/stalk cell differentiation, resulting in delayed retinal vascular development. In addition, Sptlc1 ECKO mice had reduced pathological retinal neovascularization in the oxygen-induced retinopathy model, suggesting that EC SL produced from the de novo pathway are needed for efficient VEGF signaling within the vascular system. Post-natal deletion of the EC Sptlc1also showed cell-extrinsic effects, including rapid reduction of several SL metabolites in plasma, red blood cells and peripheral organs (lung and liver) but not in the retina, part of the central nervous system (CNS). In the liver, EC de novo SL synthesis was required for acetaminophen-induced ceramide elevation and hepatotoxicity. These results suggest that EC-derived SL metabolites are in constant flux between the vasculature, circulatory elements, and parenchymal cells of non-CNS organs. Taken together, our data point to the central role of the endothelial SL biosynthesis in maintaining vascular development and neovascular proliferation, non-CNS tissue metabolic homeostasis and hepatocyte response to stress.

developmental biology↗