Recent studies have shown that dietary phospholipids, especially phosphatidylcholine and phosphatidylserine, have various beneficial biological effects. However, there are not enough data concerning the physiological function of dietary phosphatidylinositol (PI). The metabolic syndrome, a cluster of metabolic abnormalities such as dyslipidemia, diabetes mellitus, and hypertension, is a widespread and increasingly prevalent disease in industrialized countries. Nonalcoholic fatty liver disease (NAFLD) is often associated with features of the metabolic syndrome. NAFLD describes the spectrum of liver damage ranging from hepatic steatosis to steatohepatitis, liver fibrosis, and cirrhosis, and it is emerging as the most common liver disease worldwide. The present study examined whether dietary PI protects Zucker ( fa/ fa) rats from the metabolic syndrome. For 4 weeks, rats were fed semisynthetic diets containing either 7% soybean oil or 5% soybean oil plus 2% PI. Dietary PI markedly prevented the development of hepatomegaly and hepatic steatosis and lowered hepatic injury markers in serum. Additionally, hyperinsulinemia was relieved by the feeding of dietary PI in Zucker rats. These effects were attributable to an increase in serum adiponectin, enhancement of fatty acid beta-oxidation, and suppression of mRNA expression of inflammatory genes in the liver. This is the first report that dietary PI increases serum adiponectin level and prevents the development of NAFLD in a rat model of the metabolic syndrome.

Triglycerides (TG) consisting of highly purified (>97%) n-3 series highly unsaturated fatty acids, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA), were administered to C57BL/KsJ-db/db mice for 4 weeks by pair-feeding to compare their effects on lipid metabolism and to evaluate the effects of DPA on lipid metabolism. The hepatic TG level and total amount was decreased by treatment with DHA and DPA compared to the control. The efficacy of DPA was greater than that of EPA, but less than that of DHA. In contrast, EPA had the greatest serum TG reducing effect. The hepatic cytosol fraction of the DHA-treated group contained the lowest fatty acid synthase (FAS) and malic enzyme (ME) activity levels. Furthermore, the DHA-treated group contained the highest serum adiponectin concentrations. These findings indicate that the strong hepatic TG-lowering effect of DHA is due to the suppression of TG synthesis. The same tendencies were observed in DPA-treated mice, and the effect was stronger than that observed in EPA-treated mice, but equivalent to that observed in DHA-treated mice. Based on these results, DPA possesses lipid metabolism-improving effects. The beneficial effects of DPA for lipid metabolism were not superior to those of EPA and DHA, and the effect was always intermediate between those of EPA and DHA.

A regimen of pirfenidone combined with corticosteroids and rhTM may improve survival in patients with AE-IPF.