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Omega-3 long-chain polyunsaturated fatty acids (ω3PUFA) have been shown to be antiinflammatory in the attenuation of hepatocellular injury. Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear receptor transcription factor that inhibits the activation of nuclear factor κB, thereby repressing inflammation, and ωPUFA are PPARα ligands. The purpose of this study was to determine if ω3PUFA attenuate bile acid-induced apoptosis via PPARα.Human hepatocellular carcinoma (HepG2) cells were treated with chenodeoxycholic acid (CDCA) ± ω3PUFA. Activation of PPARα was evaluated, and expression of PPARα, farnesoid X receptor, liver X receptor alpha (LXRα), and retinoid X receptor mRNA was evaluated by reverse-transcriptase PCR.PPARα activation was increased in HepG2 cells treated with ω3PUFA, and decreased in the presence of CDCA when compared with untreated cells. PPARα mRNA was reduced by 67% with CDCA and restored to the level of control with ω3PUFA. LXRα mRNA increased twofold with CDCA treatment and was significantly reduced by ω3PUFA.Expression of PPARα, as well as LXRα mRNA levels, was reduced with CDCA treatment and restored with the addition of ω3PUFA. These results suggest that PPARα and LXRα may be mediators by which ω3PUFA attenuate bile acid-induced hepatocellular injury.

The purpose of this study was to determine the effects of dietary fatty acids of varying chain lengths and degrees of saturation on intestinal apolipoprotein (apo) B and A-I expression in the newborn piglet. Two-day-old female piglets received one of three isocaloric formulas containing 48% of total calories (120 kcal/kg/24 h) as medium-chain triglycerides (MCT) from MCT oil, intermediate-chain saturated triglycerides (ICST) from coconut oil, or long-chain polyunsaturated triglycerides (LCPUT) from safflower oil by continuous duodenal infusion for 24 h. After in situ radiolabeling, jejunal and ileal mucosal apo B-48 and A-I were immunoprecipitated, and synthesis was expressed as percentage of total protein synthesis. Mucosal apo B and A-I mass was measured by ELISA as nanograms of apoprotein/microgram of total protein. Fifty percent less apo B jejunal synthesis was present in the ICST group versus the MCT and LCPUT groups (0.67 +/- 0.07, 1.19 +/- 0.20, and 1.25 +/- 0.15, respectively, mean +/- SEM, p0.05). Jejunal apo B mass was lower in the MCT group versus the ICST and LCPUT groups (0.10 +/- 0.02, 0.21 +/- 0.03, and 0.16 +/- 0.03, respectively, p0.05). Ileal apo B synthesis was lowest in the ICST group. No differences were found in ileal apo B mass. Two-fold higher jejunal apo A-I synthesis was found in the LCPUT group versus the MCT and ICST groups (14.18 +/- 1.69, 7.56 +/- 2.63, and 6.36 +/- 0.58, respectively, p0.01). No differences were found for jejunal apo A-I mass. In the ileum, the only difference was a higher apo A-I mass in the LCPUT group (p0.05). We conclude that in the newborn piglet intestinal apo B and A-I expression is acutely and differentially regulated by dietary lipid varying in fatty acid chain length and saturation. The patterns of regulation are complex and vary among specific apolipoproteins and regions of the small intestine and include co- and posttranslational mechanisms.

To determine the effects of hormones and epidermal growth factor (EGF) on the small intestinal synthesis of apolipoproteins B-48, A-I, and A-IV in the neonatal mammal, apolipoprotein synthesis by proximal jejunal explants from 2-d-old female piglets was studied in tissue culture. Initial comparison studies with various media showed optimal total protein and apo A-I synthesis with Williams' medium E without fetal bovine serum. Sets of explants were prepared containing EGF and various hormones in the medium. After 35S-methionine radiolabeling, explants were homogenized, and specific apolipoprotein synthesis was quantitated by immunoprecipitation as the percentage of total protein synthesis. Apo B-48 synthesis was not affected by any additives except the combination of EGF and hydrocortisone, which slightly decreased synthesis. Apo A-I synthesis was significantly increased by EGF. This EGF-induced increase in apo A-I synthesis was blunted by concomitant treatment with hydrocortisone. In contrast, the combination of insulin and hydrocortisone induced a significant increase in apo A-I synthesis. Although EGF and insulin modestly increased apo A-IV synthesis, the combination of insulin and hydro- cortisone treatment up-regulated apo A-IV synthesis by 2.6-fold. Thyroid hormone lacked effect on synthesis of any of the apolipoproteins. EGF, glucocorticoids, and insulin may play regulatory roles in the developmental expression of apolipoprotein synthesis in the neonatal small intestine.

To determine the effects of dietary and bili- ary lipid absorption on intestinal apo B-48 and apo A-I synthesis in the newborn piglet, 2-d-old female piglets were prepared with a duodenal infusion catheter. After recovery, animals were given either low triglyceride (Vivonex; VIV group) or high triglyceride (Intralipid; FAT group) diets by continuous intraduodenal infusion for 24 h. A bile- diverted group was also studied. Segments of proximal jejunum and distal ileum were then pulse-radiolabeled in vivo with 'H-leucine. Mucosal apo B-48 and apo A-I were immunoprecipitated, and apoprotein synthesis was ex- pressed as percentage of total protein synthesis. Mucosal apoprotein content (ng apoprotein/pg total protein) was measured by competitive ELISA assays. In jejunum and ileum, apo B-48 synthesis was not different in the three groups. However, apo B content increased 2.4-fold in je- junum and 1.7-fold in ileum in the FAT group compared with the VIV group. Immunoblotting revealed the majority of jejunal apo B to be apo B-48, not apo B-100 from contaminating plasma lipoproteins, in all three experimen- tal groups. Bile-diverted animals had decreased jejunal apo B content compared with the VIV group. Jejunal apo A-I synthesis and content were approximately 2-fold higher in FAT animals compared with the VIV group. Although ileal apo A-I synthesis was also 2-fold higher in the FAT group, apo A-I content was not different from the VIV group. Neither jejunal nor ileal apo A-I synthesis was significantly affected by bile diversion, even though jejunal apo A-I content was decreased by over two thirds compared with the VIV animals. In the newborn piglet, intestinal synthesis of apo B-48 and apo A-I is differentially regulated by luminal lipid absorption. Although fat feeding and bile diversion regulate mucosal apo B-48 content, synthesis is unchanged, indicating a posttranslational regulatory mech- anism. In contrast, apo A-I synthesis generally parallels mucosal apo A-I content except in distal ileum. Changes in jejunal apo B content and apo A-I content and synthesis parallel changes in mucosal triglyceride content. However, changes in ileal apo B content and apo A-I synthesis were not accompanied by changes in ileal triglyceride content, suggesting other regulatory factors in the distal small intestine. (Pediatr Res 29: 32-38, 1991) Abbreviations

Comparison of Histologic Methods for the Diagnosis of Pediatric Helicobacter pylori Infection

Induction of Jejunal Apolipoprotein A-I Synthesis by Dietary Phosphatidylcholine in Newborn Swine † 604

MODULATION OF APOLIPOPROTEIN SECRETION AND LIPID SYNTHESIS BY BILIARY LIPIDS IN A PORCINE INTESTINAL EPITHELIAL CELL LINE • 467

APOLIPOPROTEIN SECRETION BY A NEWBORN PIGLET INTESTINAL CELL LINE (IPEC-1) IN RESPONSE TO FATTY ACID UPTAKE. † 754

Disease states characterized by reticuloendothelial activation are associated with disordered lipoprotein metabolism. Apo A-I is the major apolipoprotein of high-density lipoproteins and is a cofactor for cholesterol esterification. Apo E is important in the receptor-mediated clearance of remnant lipoproteins. The purpose of this study was to determine the effect of cytokine treatment on cultured murine hepatocyte apo A-I and E synthesis and secretion. Primary murine hepatocytes were incubated for 48 hrs in the presence of 100 ng/ml tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1) or IL-6 (n=4 wells for each cytokine). During the terminal 4 hrs of the incubation, apo A-I and E secretion and cell content were determined by ELISA assay. Apolipoprotein synthesis and degradation over this same period were analyzed by steady-state and pulse-chase35 S-methionine radiolabelling, followed by cell homogenate and culture medium apolipoprotein immunoprecipitation, SDS PAGE, and autoradiography. Apo A-I cellular content was reduced after IL-1 and IL-6 treatment by 40%(p

Plasma lipoproteins from two female patients—patient A, 4 wk and patient B, 19 months—were examined prior to and at 1 and 5 wk after surgical correction of biliary obstruction due to choledochal cyst. The findings were correlated with standard indices of hepatic function, namely SGPT, GGTP, 5′nucleotidase, serum bile salts, and total and conjugated bilirubin. Prior to surgery in both patients plasma cholesterol, phospholipid, and triglyceride were elevated; cholesterol esters were low; high-density lipoprotein (HDL) cholesterol and apolipoprotein A-I, the major protein constituent of HDL, were subnormal; most of the plasma lipids were contained in the low-density lipoprotein density region; lipoprotein-X was present. Patient B had had a relatively brief obstruction and suffered little secondary hepatic injury. One week after surgery, plasma lipid concentrations returned to normal; apoliprotein A-I increased in the HDL density region and a concomitant rise in cholesterol esters to near normal, 65%, was observed; plasma lipids were contained predominantly in HDL; hepatic function improved markedly. Patient A had had intrauterine obstruction and suffered major hepatic injury with cirrhosis. One week after surgery, plasma lipid concentrations, cholesterol esters, low-density lipoprotein lipid predominance, and hepatic function remained essentially unchanged. Five weeks after surgery, the lipoprotein levels and composition and hepatic function were near normal. In conclusion, children with biliary obstruction have lipoprotein abnormalities similar to those seen in adult patients. These alterations are rapidly reversible with surgical relief and may be used as prognostic indicators of outcome.

We investigated the potential role of maternal VLDL as a source of fatty acids (FA) for use by the fetus using isolated perfused human placenta. Recirculating fetal and maternal perfusions of 10 cm diameter portions of 5 term placentas were used to determine the fate of 3H-(FA)triolein (TG) incorporated into human VLDL. Perfusates consisted of Kreb's bicarbonate buffer, 4% FA-free BSA, 100 mg% glucose, and 20% human RBC. The model was validated by oxygen uptake, glucose utilization, leucine transport, and BSP exclusion. VLDL was added to the maternal perfusates and circulations maintained for 2 hours. VLDL became TG depleted (62.5 ± 1.6 (SE) % to 49.0 ± 4.2) and phospholipid enriched (25.0 ± 0.9 to 37.2 ± 7.8). Scintillation counting of perfusates revealed the following: the rate of uptake of VLDL-TG by placenta was 0.76 ± 0.14 μg/g placenta/min which represents over the length of the perfusion, 11.7 ± 2.3% of the initial TG mass; of this loss, 10.0 ± 1.3% appeared in the fetal perfusate. TLC of lipid extracts from perfusate and placenta revealed 3H-FA to be distributed as follows: in placenta, monoglyceride (MG)-49.8%, diglyceride (DG)-30.2, FA-10.5, TG-6.5, and cholesteryl ester-2.9; in fetal perfusate, MG-56.7, DG-27.0, FA-14.7, and TG-1.2. We conclude maternal VLDL is metabolized by placenta via TG hydrolysis (presumably by lipoprotein lipase) and liberated partial glycerides and FA are taken up for use by placenta or transport to the fetus.