ELIZONDO, ALEJANDRA, JULIA ARAYA, RAMÓ N RODRIGO, JAIME PONIACHIK, ATTILA CSENDES, FERNANDO MALUENDA, JUAN C. DÍAZ, CINZIA SIGNORINI, CRISTIANA SGHERRI, MARIO COMPORTI, AND LUIS A. VIDELA. Polyunsaturated fatty acid pattern in liver and erythrocyte phospholipids from obese patients Obesity. 2007;15:24 -31. Objective: Our aim was to study the fatty acid (FA) composition of liver phospholipids and its relation to that in erythrocyte membranes from patients with obese nonalcoholic fatty liver disease (NAFLD), as an indication of lipid metabolism alterations leading to steatosis. Research Methods and Procedures: Eight control subjects who underwent antireflux surgery and 12 obese patients with NAFLD who underwent subtotal gastrectomy with a gastro-jejunal anastomosis in Roux-en-Y were studied. The oxidative stress status of patients was assessed by serum F 2 -isoprostanes levels (gas chromatography/negative ion chemical ionization tandem mass spectrometry). Analysis of FA composition of liver and erythrocyte phospholipids was carried out by gas-liquid chromatography. Results: Patients with NAFLD showed serum F 2 -isoprostanes levels 84% higher than controls. Compared with controls, liver phospholipids from obese patients exhibited significantly 1) lower levels of 20:4n-6, 22:5n-3, 22:6n-3 [docosahexaenoic acid (DHA)], total long-chain polyunsaturated FA (LCPUFA), and total n-3 LCPUFA, 2) higher 22:5n-6 [docosapentaenoic acid (DPAn-6)] levels and n-6/ n-3 LCPUFA ratios, and 3) comparable levels of n-6 LCPUFA. Levels of DHA and DPAn-6 in liver were positively correlated with those in erythrocytes (r ϭ 0.77 and r ϭ 0.90, respectively; p Ͻ 0.0001), whereas DHA and DPAn-6 showed a negative association in both tissues (r ϭ Ϫ0.79, p Ͻ 0.0001 and r ϭ Ϫ0.58, p Ͻ 0.01, respectively), associated with lower DHA/DPAn-6 ratios. Discussion: Obese patients with NAFLD showed marked alterations in the polyunsaturated fatty acid pattern of the liver. These changes are significantly correlated with those found in erythrocytes, thus suggesting that erythrocyte FA composition could be a reliable indicator of derangements in liver lipid metabolism in obese patients.

Carbon tetrachloride (CCl 4 )-induced hepatic fibrosis has been considered to be linked to oxidative stress and mediated by aldehydic lipid peroxidation products. In the present study, we investigated whether collagen synthesis is induced by F 2 -isoprostanes, the most proximal products of lipid peroxidation and known mediators of important biological effects. By contrast with aldehydes, F 2 -isoprostanes act through receptors able to elicit definite signal transduction pathways. In a rat model of CCl 4 -induced hepatic fibrosis, plasma F 2 -isoprostanes were markedly elevated for the entire experimental period; hepatic collagen content also increased. When hepatic stellate cells (HSCs) from normal liver were cultured with F 2 -isoprostanes in the concentration range found in the in vivo studies (10 À9 -10 À8 M), a striking increase in DNA synthesis (reversed by the thromboxane A 2 antagonist SQ 29 548), in cell proliferation and in collagen synthesis was observed. Total collagen content was similarly increased. Moreover, F 2 -isoprostanes markedly increased the production of transforming growth factor-b1 by U937 cells, considered a model of liver macrophages. The data provide evidence for the possibility that F 2 -isoprostanes generated by lipid peroxidation in hepatocytes mediate HSC proliferation and collagen production seen in hepatic fibrosis.

Our aim was to study the influence of weight loss on the fatty acid (FA) composition of liver and erythrocyte phospholipids and oxidative stress status in obese, non-alcoholic, fatty liver disease (NAFLD) patients. Seven obese NAFLD patients who underwent subtotal gastrectomy with a gastro-jejunal anastomosis in roux and Y were studied immediately and 3 months after surgery. Seven non-obese patients who underwent anti-reflux surgery constituted the control group. Serum F 2-isoprostane levels were measured by GS/NICI-MS/MS and FA composition was determined by GC. At the time of surgery, controls and obese patients exhibited a hepatic polyunsaturated fatty acid (PUFA) pattern that correlated with that of erythrocytes. Three months after surgery, NAFLD patients lost 21% of initial body weight; serum F 2-isoprostane levels decreased by 76%; total PUFA, long-chain PUFA (LCPUFA), n-3 PUFA, and n-3 LCPUFA increased by 22, 29, 81, and 93%, respectively; n-6/n-3 LCPUFA ratio decreased by 51%; docosahexaenoic acid/docosapentaenoic acid ratio increased by 19-fold; and the n-3 product/precursor ratio (20: 5 + 22: 5 + 22: 6)/18: 3 increased by 164% (p<0.05). It is concluded that weight loss improves the n-3 LCPUFA status of obese patients in association with significant amelioration in the biomarkers of oxidative stress, membrane FA insaturation, and n-3 LCPUFA biosynthesis capacity, thus representing a central therapeutic issue in the improvement of obesityrelated metabolic alterations involved in the mechanism of hepatic steatosis.

Nonprotein-bound iron (NPBI) and F 2 -isoprostanes, reliable markers of oxidative stress, are increased in plasma of newborns and inversely correlated to the gestational age. Because NPBI represents a pro-oxidant stimulus in plasma, we test the hypothesis that the entity of lipid peroxidation is related with NPBI concentrations. Plasma levels of free, esterified, and total F 2 -isoprostanes were investigated in relation to NPBI levels in 59 newborns and 16 healthy adults. The pro-oxidant role of iron was ascertained in vitro, by measuring all the forms of F 2 -isoprostanes after incubation with ammonium iron sulfate. Significant positive correlations were found between NPBI and total as well as esterified F 2 -isoprostanes in plasma of the newborns. The addition of ammonium iron sulfate induced a marked increase in all the forms of F 2 -isoprostanes after 2 hours of incubation. The higher NPBI concentration, the higher F 2 -isoprostanes levels. An increase NPBI dose dependent in total F 2 -isoprostanes formation was observed in dialyzed low density lipoprotein from adult plasma. The results clearly show that once NPBI is generated, whatever its source, it is capable of inducing oxidative stress. NPBI-induced oxidative stress may contribute to the morbidity in preterm infants that are particularly susceptible to free radical damage. (Pediatr Res 63: 287-291, 2008)