Adipose saturation reduces lipotoxic systemic inflammation and explains the obesity paradox

Obesity sometimes seems protective in disease. This obesity paradox is predominantly described in reports from the Western Hemisphere during acute illnesses. Since adipose triglyceride composition corresponds to long-term dietary patterns, we performed a meta-analysis modeling the effect of obesity on severity of acute pancreatitis, in the context of dietary patterns of the countries from which the studies originated. Increased severity was noted in leaner populations with a higher proportion of unsaturated fat intake. In mice, greater hydrolysis of unsaturated visceral triglyceride caused worse organ failure during pancreatitis, even when the mice were leaner than those having saturated triglyceride. Saturation interfered with triglyceride’s interaction and lipolysis by pancreatic triglyceride lipase, which mediates organ failure. Unsaturation increased fatty acid monomers in vivo and aqueous media, resulting in greater lipotoxic cellular responses and organ failure. Therefore, visceral triglyceride saturation reduces the ensuing lipotoxicity despite higher adiposity, thus explaining the obesity paradox.

A secreted lipase encoded by LIP1 is necessary for efficient use of saturated triglyceride lipids in Fusarium graminearum

A triglyceride lipase gene LIP1 was identified in the genome of Fusarium graminearum strain PH-1. The predicted protein encoded by LIP1 contains 591 amino acid residues with a putative N-terminal signal peptide and shows 57 and 40–44 % identity to a Botrytis cinerea lipase and five Candida rugosa lipases, respectively. Yeast cells overexpressing LIP1 showed lipolytic activity against a broad range of triglyceride substrates. Northern blot analyses revealed that expression of LIP1 was activated in planta during the fungal infection process. LIP1 expression was strongly induced in minimal medium supplemented with wheatgerm oil, but only weakly induced by olive oil and triolein. In contrast, supplementation with other carbon sources, including glucose, sucrose, apple pectin and wheat cell-wall material, did not induce LIP1 expression. Saturated fatty acids were the strongest inducers for LIP1 expression and this induction was suppressed proportionally by the presence of the unsaturated fatty acid. To determine the potential function of LIP1, gene replacement was conducted on strain PH-1. When compared with wild-type PH-1, ΔLIP1 mutants showed greatly reduced lipolytic activities at the early stage of incubation on minimal medium supplemented with either saturated or unsaturated lipid as the substrate, indicating that LIP1 encodes a secreted lipase for exogenous lipid hydrolysis. Moreover, the ΔLIP1 mutants exhibited growth deficiency on both liquid and solid minimal media supplemented with the saturated triglyceride tristearin as the sole carbon source, suggesting that LIP1 is required for utilization of this substance. Despite these differences, no variation in disease symptoms between the ΔLIP1 mutants and the wild-type strain was observed on susceptible cereal hosts.

The effect of change from low-roughage to high-roughage diets on rumen fermentation, blood composition and milk fat secretion in the cow

1. Changing cows from a diet with low hay and high flaked maize content, which depressed milk fat secretion, to a high-roughage diet resulted in increased milk fat secretion and in changes in the pattern of rumen fermentation and in the composition of the blood plasma.2. During the 1st week following the change in diet the proportions of propionic and valeric acids in the rumen decreased and the proportion of acetic acid increased. These changes in rumen volatile fatty acids were associated with decreases in the concentration of lactic acid, increases in pH and increases in the rate of breakdown of cotton threads in the ventral sac of the rumen. After 1 week, only minor fluctuations in the proportions of volatile fatty acids occurred from day to day.3. The percentage of fat in the milk increased over a period of 3 weeks following the change in diet and, with the exception of linoleic acid which decreased, the yields of all fatty acids in milk progressively increased over this period. The increase in yield of oleic acid was relatively much smaller than the increases in yield of saturated acids.4. The concentrations in blood plasma of acetic acid and β-hydroxybutyric acid increased in two cows and, in all cows, saturated triglyceride fatty acids increased, whereas the concentrations of the unsaturated triglyceride fatty acids decreased, during the 1st week after change to the high-roughage diet. The recovery in milk fat secretion is discussed in relation to the observed changes in rumen fermentation and blood composition.