Modulation of intracellular machinery by beta-glycolipids is associated with alteration of NKT lipid rafts and amelioration of concanavalin-induced hepatitis.
The integrity of lipid rafts in cell membranes is important for signal transduction.


OBJECTIVE
To determine the distinct effects of beta-glycolipids on the composition of lipid rafts in natural killer T (NKT) cells and on the level of expression of flotillin-2, leukocyte-specific protein tyrosine kinase (Lck), and STAT1-associated pathways.


METHODS
The effects of glycolipids were determined by composition analysis of the raft domains, FACS analysis of the distribution patterns for the raft ganglioside, GM1, and fluorescence microscopy of raft patching. To evaluate the effects of the immune environment on glycolipid-associated alteration of lipid rafts, hepatitis was induced by an intravenous injection of concanavalin A (ConA) in mice treated with various glycolipids.


RESULTS
The administration of beta-glucosylceramide, beta-lactosylceramide, and a combination of both significantly altered GM1 content in lymphocyte membranes in an environment-dependent manner. These effects were associated with altered expression levels of flotillin-2, Lck, and STAT1, and with a significant decrease in intrahepatic CD8+ lymphocyte trapping and the alleviation of ConA-induced hepatitis. The administration of alpha-glycolipids failed to induce similar effects.


CONCLUSIONS
The alteration in the expression levels of flotillin-2, Lck, and STAT1 that occurs concomitantly with changes in lipid raft composition and structure following the administration of beta-glycolipids in ConA-induced hepatitis is microenvironment-dependent and is associated with decreased intrahepatic CD8(+) T lymphocyte trapping and amelioration of immune-mediated hepatitis.
Lalazar
Gadi
G
Liver Unit, Department of Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel.
Ben Ya'acov
Ami
A
Lador
Adi
A
Livovsky
Dan M
DM
Pappo
Orit
O
Preston
Sarah
S
Hareati
Menahem
M
Ilan
Yaron
Y
D000818:Animals; D003208:Concanavalin A; D006017:Glycolipids / Q000494:pharmacology*; D006520:Hepatitis, Animal / Q000139:chemically induced* / Q000276:immunology* / Q000473:pathology; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D008297:Male; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000378:metabolism
D006017:Glycolipids; D008565:Membrane Proteins; C106354:flotillins; D003208:Concanavalin A; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)