BACKGROUND: The source of accumulated lipids in the foam cells of xanthoma is primarily the lipoproteins existing in the lesional dermis. OBJECTIVE: This study was designated to clarify the contribution of low density lipoprotein (LDL) density substances existing in xanthoma tissue to foam cell formation. METHODS: An LDL density fraction was obtained from homogenized rabbit experimental xanthoma tissue. Biochemical and functional characteristics of xanthoma-extracted LDL density substance were examined. The in vivo foam cell-inducing ability of xanthoma-extracted LDL density substance was examined microscopically at the intradermal injection site. RESULTS: Xanthoma-extracted LDL density substance showed more negatively charged mobility on agarose gel electrophoresis than plasma native LDL. A small amount of aggregated material remained at the origin on agarose gel electrophoresis. Xanthoma-extracted LDL density substance contained much higher level of lipid peroxides than native LDL. Mouse peritoneal macrophages internalized xanthoma-extracted LDL density substance extensively and transformed into foam cells by incubation with xanthoma-extracted LDL density substance. Intradermal injection of the xanthoma-extracted LDL density substance induced foam cell infiltration in the skin of a normolipemic rabbit. CONCLUSION: LDL density substances prepared ex vivo from experimental xanthoma tissue contained lipid-protein complexes that have physiochemical properties of oxidized LDL. The lipid-protein complexes were incorporated into foam cells. The substances were considered to contribute to foam cell recruitment during the persistence of xanthoma lesions.
BACKGROUND: The source of accumulated lipids in the foam cells of xanthoma is primarily the lipoproteins existing in the lesional dermis. OBJECTIVE: This study was designated to clarify the contribution of low density lipoprotein (LDL) density substances existing in xanthoma tissue to foam cell formation. METHODS: An LDL density fraction was obtained from homogenized rabbit experimental xanthoma tissue. Biochemical and functional characteristics of xanthoma-extracted LDL density substance were examined. The in vivo foam cell-inducing ability of xanthoma-extracted LDL density substance was examined microscopically at the intradermal injection site. RESULTS:Xanthoma-extracted LDL density substance showed more negatively charged mobility on agarose gel electrophoresis than plasma native LDL. A small amount of aggregated material remained at the origin on agarose gel electrophoresis. Xanthoma-extracted LDL density substance contained much higher level of lipid peroxides than native LDL. Mouse peritoneal macrophages internalized xanthoma-extracted LDL density substance extensively and transformed into foam cells by incubation with xanthoma-extracted LDL density substance. Intradermal injection of the xanthoma-extracted LDL density substance induced foam cell infiltration in the skin of a normolipemic rabbit. CONCLUSION: LDL density substances prepared ex vivo from experimental xanthoma tissue contained lipid-protein complexes that have physiochemical properties of oxidized LDL. The lipid-protein complexes were incorporated into foam cells. The substances were considered to contribute to foam cell recruitment during the persistence of xanthoma lesions.