title: Cellular cholesterol enrichment impairs T cell activation and chemotaxis.
abstract: Human aging is associated with an increase in immune cell cholesterol levels, independent of circulating cholesterol levels. The effects of such an increase in membrane cholesterol on lipid raft-associated immune cell function have not been investigated. We sought to examine the effects of in vitro cholesterol loading on two known lipid raft-associated pathways of T cells, namely T cell activation and chemokine stimulation. Using beta-cyclodextrin (BCD) as a vehicle, we were able to rapidly load cholesterol onto human T cell lines and primary peripheral blood T cells without inducing significant cell toxicity. Loading of cholesterol to four-fold that of normal levels induced significant inhibition of intracellular calcium mobilization by both alphaCD3 and SDF-1alpha. Cholesterol-loaded peripheral T cells were completely unresponsive to alphaCD3/alphaCD28 stimulation, demonstrating no increase in IL-2, GM1 expression or cell size. T cell polarization of lipid rafts to alphaCD3/alphaCD28 beads was also impaired. In addition, cholesterol loading potently inhibited SDF-1alpha-induced chemotaxis. We propose that excess membrane cholesterol could potentially disrupt raft-related cell functions downstream of receptor triggering and that the loss of cholesterol regulation of aging immune cells could contribute to immune cell senescence.
authors.affiliation: Laboratory of Immunology, National Institute on Aging, NIH, Intramural Research Program, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA. taubd@grc.nia.nih.gov
authors.forename: Dzung H
authors.initials: DH
authors.lastname: Nguyen
authors.forename: Juan C
authors.initials: JC
authors.lastname: Espinoza
authors.forename: Dennis D
authors.initials: DD
authors.lastname: Taub
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001692:Biological Transport / Q000502:physiology; D017252:CD3 Complex / Q000276:immunology / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D016764:Cell Polarity; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000502:physiology; D002634:Chemotaxis, Leukocyte; D002784:Cholesterol / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology*; D021962:Membrane Microdomains / Q000502:physiology; D008863:Microspheres; D020033:Protein Isoforms / Q000276:immunology / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; C515255:CXCL12 protein, human; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D020033:Protein Isoforms; D002784:Cholesterol; D002118:Calcium