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

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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