LDL receptor–mediated lipoprotein uptake fuels human CD4+ T cell polarization toward a c-MAF/IL-10– and FOXP3-driven phenotype
Angela Markovska, Niels S. van Heusden, Dagmar Duijzer, Alejandra Bodelón, Greta Rogani, Enric Mocholi, Edwin C.A. Stigter, Can Gulersonmez, Sander Kooijman, Leonie Van der Zee, Monique T. Mulder, Jeanine E. Roeters van Lennep, Patrick C.N. Rensen, Jorg van Loosdregt, Sebastiaan J. Vastert, Noam Zelcer, Marianne Boes, Henk S. Schipper
Angela Markovska, Niels S. van Heusden, Dagmar Duijzer, Alejandra Bodelón, Greta Rogani, Enric Mocholi, Edwin C.A. Stigter, Can Gulersonmez, Sander Kooijman, Leonie Van der Zee, Monique T. Mulder, Jeanine E. Roeters van Lennep, Patrick C.N. Rensen, Jorg van Loosdregt, Sebastiaan J. Vastert, Noam Zelcer, Marianne Boes, Henk S. Schipper
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Research Article Cell biology Immunology

LDL receptor–mediated lipoprotein uptake fuels human CD4+ T cell polarization toward a c-MAF/IL-10– and FOXP3-driven phenotype

Abstract

Human CD4+ T cells utilize nutrients, including lipids, to support their activation and polarization. Considering the pivotal role of lipoproteins in lipid transport, we reasoned that lipoprotein uptake and processing could effect CD4+ T cell function. Here, we demonstrate that activation of human CD4+ T cells induced expression of LDL receptor (LDLR) to facilitate LDLR-mediated endocytosis of LDL. Degradation of surface LDLR on CD4+ T cells with PCSK9 hampered activation and proliferation of the cells. Lipoprotein deprivation or blocking of lysosomal cholesterol egress impaired activation of mechanistic target of rapamycin complex 1 (mTORC1), affecting CD4+ T cell activation and proliferation. Furthermore, lipoprotein deprivation of cultured primary CD4+ T cells lead to reduced expression of c-MAF and FOXP3, key transcription factors for IL-10, accompanied by reduced IL-10 secretion. The pivotal role of LDLR-mediated lipoprotein uptake for mTORC1 activity, c-MAF and FOXP3 expression, and IL-10 secretion was confirmed using LDLR-dysfunctional CD4+ T cells from patients with homozygous familial hypercholesterolemia. Our study offers valuable insights into the lipoprotein metabolism of human CD4+ T cells and their reliance on the LDLR pathway for activation and polarization, a feature that may be leveraged to modulate CD4+ T cell function.

Authors

Angela Markovska, Niels S. van Heusden, Dagmar Duijzer, Alejandra Bodelón, Greta Rogani, Enric Mocholi, Edwin C.A. Stigter, Can Gulersonmez, Sander Kooijman, Leonie Van der Zee, Monique T. Mulder, Jeanine E. Roeters van Lennep, Patrick C.N. Rensen, Jorg van Loosdregt, Sebastiaan J. Vastert, Noam Zelcer, Marianne Boes, Henk S. Schipper

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Figure 2

SREBP-2 drives endocytosis and lysosomal processing of lipoproteins by activated CD4+ T cells.

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SREBP-2 drives endocytosis and lysosomal processing of lipoproteins by a...
(A) Schematic of SREBP-2 pathway. (B) Representative confocal images of SREBP-2 and Hoechst staining in resting or activated CD4+ T cells (anti-CD3/CD28, 24 hours). Where indicated, cells were treated with PF-429242 (10 μM). Quantification of the SREBP-2 nuclear/cytoplasmic intensity (n = 3; 5 images/condition). Kruskal-Wallis test with Dunn’s multiple comparisons test (****P < 0.0001). Scale bar: 10 �m. (C) LDLR mRNA in CD4+ T cells activated for 24 hours with and without 25-HC (5 μM) or PF-429242 (10 μM). Kruskal-Wallis with Dunn’s test (*P < 0.05; n = 3). (D) Cell surface LDLR on CD4+ T cells activated for 24 hours. Kruskal-Wallis with Dunn’s multiple comparisons test (**P < 0.01, ****P < 0.0001; n = 6). (E) LDLR and GAPDH levels measured by Western blot in activated CD4+ T cells (anti-CD3/CD28, 24 hours). (F) Cells were activated and loaded with LDL-DyLight for 16 hours. Where indicated, cells were treated with 25-HC. Kruskal-Wallis with Dunn’s multiple comparisons test (**P < 0.01; n = 3). (G) Schematic of the lipoprotein-pHrodo uptake. Uptake of (H) LDL-pHrodo and (I) VLDL-pHrodo measured by flow cytometry, where CD4+ T cells were activated for 24 hours, followed by a 2-hour culture in lipoprotein-deprived medium and 2-hour incubation with lipoprotein-pHrodo. One-way ANOVA with Dunnett’s multiple comparisons test (****P < 0.0001); n = 9 (H) and n = 6 (I). (J) Cells were activated, where indicated treated with 25-HC for 24 hours, followed by 2-hour LDL-pHrodo loading. One-way ANOVA with Tukey’s multiple comparisons test (****P < 0.0001; n = 6). (K) Schematic of NPC1 and U18666A. (L) Forward-scatter area (FSC-A)/side-scatter area (SSC-A) plots of CD4+ T cells activated for 24 hours with or without U18666A (2 μg/mL). (M) Cell surface LDLR expression on CD4+ T cells measured by flow cytometry. Mann-Whitney U test (**P < 0.01; n = 6). (N and O) Uptake of LDL-pHrodo and VLDL-pHrodo by CD4+ T cells. Ordinary 1-way ANOVA with Dunnett’s multiple comparisons test (**P < 0.01, ****P < 0.0001; n = 6).