Modulation of peritoneal macrophage activity by the saturation state of the fatty acid moiety of phosphatidylcholine

To determine the effects of saturated and unsaturated fatty acids in phosphatidylcholine (PC) on macrophage activity, peritoneal lavage cells were cultured in the presence of phosphatidylcholine rich in saturated or unsaturated fatty acids (sat PC and unsatPC, respectively), both used at concentrations of 32 and 64 ìM. The treatment of peritoneal macrophages with 64 ìM unsat PC increased the production of hydrogen peroxide by 48.3% compared to control (148.3 ± 16.3 vs 100.0 ± 1.8%, N = 15), and both doses of unsat PC increased adhesion capacity by nearly 50%. Moreover, 64 ìM unsat PC decreased neutral red uptake by lysosomes by 32.5% compared to the untreated group (67.5 ± 6.8 vs 100.0 ± 5.5%, N = 15), while both 32 and 64 ìM unsat PC decreased the production of lipopolysaccharide-elicited nitric oxide by 30.4% (13.5 ± 2.6 vs 19.4 ± 2.5 ìM) and 46.4% (10.4 ± 3.1 vs 19.4 ± 2.5 ìM), respectively. Unsat PC did not affect anion production in non-stimulated cells or phagocytosis of unopsonized zymosan particles. A different result pattern was obtained for macrophages treated with sat PC. Phorbol 12-miristate 13-acetate-elicited superoxide production and neutral red uptake were decreased by nearly 25% by 32 and 64 ìM sat PC, respectively. Sat PC did not affect nitric oxide or hydrogen peroxide production, adhesion capacity or zymosan phagocytosis. Thus, PC modifies macrophage activity, but this effect depends on cell activation state, fatty acid saturation and esterification to PC molecule and PC concentration. Taken together, these results indicate that the fatty acid moiety of PC modulates macrophage activity and, consequently, is likely to affect immune system regulation in vivo.

Phosphatidylcholine stimulates the activity of UDP-Gal beta 1-4 galactosyltransferase in normal human kidney proximal tumour cells.

Effects of various lipid components of low density lipoproteins (LDL) and serine on the regulation of UDP-Gal-beta 1-4-galactosyltransferase (GalT-2) activity have been investigated in normal proximal tubular (PT) cells. Addition of exogenous serine (0.1-0.75 mM), cholesterol (0-200 micrograms/ml medium), linoleic acid and oleic acid (0.1-0.75 mM) for 4 hr at 37 degrees C did not suppress the activity of GalT-2 in PT cells. Similarly, incubation of cells with glucosylceramide and lactosylceramide (25-50 micrograms/ml medium) did not alter GalT-2 activity in cells as compared to control. In contrast, palmitic acid (0-0.75 mM), phosphatidylethanolamine and sphingomyelin (0-200 micrograms/ml) stimulated GalT-2 activity by 20-36% as compared to control. Incubation of PT cells with D-alpha-dipalmitoyl phosphatidylcholine (0-200 micrograms/ml medium) also stimulated the activity of GalT-2, maximum stimulation (200%) occurring with 25 micrograms phosphatidylcholine/ml medium. However, at a higher concentration (200 micrograms/ml), the stimulation of the activity of GalT-2 was in the order of 27% compared to control. Dioleylphosphatidylcholine did not alter GalT-2 activity in PT cells. Thus, it is concluded that (i) various lipid components, sphingosine and serine present in LDL are not involved in the LDL-mediated suppression of GalT-2 activity in normal PT cells, and (ii) stringent structural requirements in the phosphatidylcholine molecule are necessary to exert a time and concentration dependent stimulation of GalT-2 activity.

Effect of dietary columbinic acid on the fatty acid composition and physical membrane properties of different tissues of EFA- deficient rats

Se estudió el efecto del agregado de ácido columbínico (5 trans, 9 cis, 12 cis octadeca-trienoico) a una dieta libre de grasas sobre la composición de ácidos grasos de distintos tejidos de rata, y estos datos se correlacionaron con las propiedades físicas de dichos tejidos. La ausencia de lípidos en la dieta produjo cambios en la composición de ácidos grasos que son característicos de la deficiencia de ácidos grasos esenciales (AGE). Se observó un incremento significativo del porcentaje relativo de ácidos grasos monoenoicos acompañado de una disminución de los ácidos linoleico y araquidónico y un aumento del ácido eicosa-5,8,11-trienoico en los homogenatos de hígado riñon, pulmón y bazo. El ácido columbínico agregado a una dieta libre de grasas durante 24 ó 48 horas se incorporó en los distintos tejidos, elongándose parcialmente al ácido eicosa-7 trans 11 cis, 14 cis-trienoico, pero sin ser desaturado. El ácido columbínico modificó el perfil de composición de ácidos grasos de los lípidos en los distintos tejidos, de manera tal que su porcentaje de distribución fue similar al observado en los animales no deficientes en AGE, excepto por el descenso del ácido linoleico. La ausencia de lípidos en la dieta produjo un incremento en la anisotropía de fluorescencia determinada con excitación continua (rs) del 1,6-difenil-1,3,5-hexatrieno (DPH) en microsomas hepáticos, que se corrigió con la administración de ácido columbínico durante 24 hr. Se concluye que el ácido columbínico produjo un efecto favorable de corto alcance sobre las propiedades físicas de la membrana microsomal hepática (rs) atribuible a las modificaciones en la composición de ácidos grasos. El ácido columbínico, por lo tanto, induciría también un efecto favorable a corto plazo sobre la producción de eicosanos, pero no así a largo plazo