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 3

LDLR-mediated lipoprotein uptake by CD4+ T cell fuels their activation and proliferation.

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LDLR-mediated lipoprotein uptake by CD4+ T cell fuels their activation a...
CD4+ T cells were activated with anti-CD3/CD28 Dynabeads and cultured in control (ctrl) medium, lipoprotein-deprived medium, or lipoprotein-deprived medium supplemented with LDL (10 μg/mL). Where indicated, cells were treated with U18666A (2 μg/mL) or PF-420242 (10 μM). (A) Cell surface expression of CD40L and ICAM1 measured with flow cytometry. The statistical analysis was done on the area under the curve (AUC). One-way ANOVA with Šídák’s multiple comparisons test, (*P < 0.05, **P < 0.01; n = 3). (B and C) Representative flow cytometry histograms of the CellTrace Violet dilution. For quantification, we show the proliferation index calculated by the proliferation tool (FlowJo). (B) Kruskal-Wallis with Dunn’s multiple comparisons test (*P < 0.05, ****P < 0.0001; n = 9). (C) One-way ANOVA with Dunnett’s multiple comparisons test (***P < 0.001; n = 9). (D) PCSK9 levels measured with ELISA in the supernatant from HEK293T cells added to the CD4+ T cells (nontransfected cell line and cell line overexpressing PCSK9). Cells were cultured in T cell medium for 24 hours before starting to add the supernatant to the CD4+ T cells. (E) LDLR cell surface levels measured on CD4+ T cells with flow cytometry. Cells were activated with anti-CD3/CD28 Dynabeads for 24 or 48 hours and cultured in supernatant from HEK293T cells (nontransfected cell line and cell line overexpressing PCSK9). (F) CD69 and (G) CD25 cell surface levels measured on the CD4+ T cells with flow cytometry. (H) Representative flow cytometry histograms of CellTrace Violet dilution. Cells were activated for 4 days with anti-CD3/CD28. For quantification, we show the proliferation index calculated by the proliferation tool (FlowJo). (D–H) Unpaired t tests (**P < 0.01, ***P < 0.001, ****P < 0.0001; n = 3).