Fat-free Group Research Articles

Investigation of Impact Induced By AML1-ETO on Self-Renewal and Differentiation of Hematopoietic Stem and Progenitor Cells in Pre-Leukemic Stage

AML1-ETO fusion gene is the most common cytogenetic subtype of AML, which occurs in approximately 15% of acute myeloid leukemia (AML) patients. More than 85% of patients could achieve complete remission after induction chemotherapy. However, it was less effective on the patients over the age of 60 who cannot tolerate standard chemotherapy. And nearly 30% of patients relapsed eventually with a dismal outcome. Therefore, identification of the initiating abnormal cells to inhibit the early occurrence induced by AML1-ETO is an urgent problem. In this study, an inducible conditional AML1-ETO knock-in murine model (Aml1Eto/+; Mx1-Cre) was successfully established, hereafter called AEKI. The stage of malignant transformation in hematopoietic stem and progenitor cells (HSPC) was identified. We found that the absolute number of LT-HSCs (1.43×106 vs 4.85×103, p<0.0001), ST-HSCs (7.90×106 vs 1.88×104, p<0.0001) and MPPs (6.07×105 vs 1.82×104, p=0.0358) in bone marrow (BM) increased significantly in AEKI group compared with that of control group, while CMPs (8.13×103 vs 1.83×105, p=0.0029), GMPs (8.48×103 vs 3.12×105, p=0.0026) and MEPs (1.25×104 vs 2.03×105, p=0.001) decreased. It suggested that the activation of AML1-ETO in vivo resulted in excessive accumulation of HSCs and differentiation blockage from HSCs to HPCs. However, AML1-ETO alone was insufficient to induce the onset of overt leukemia after 300-day observation of survival. Furthermore, the characteristics of AEKI HSPCs in the pre-leukemic stage were investigated. Colony forming assay (CFC) was performed to evaluate the stemness of HSCs in vitro. The equivalent of 2×103 LT-HSCs were isolated from BM of each group and plated for 14 days. AEKI LT-HSCs gave rise to dysplastic colonies and lost replating capability compared to that of control group (colony counts: 19.33 vs 30.17, p=0.016). Moreover, a progressive decrease in PB chimerism was observed in AEKI recipients via competitive transplantation assay in vivo (15.8% vs 62.5%, p<0.0001), for which BM cellularity exhibited a significant decrease (7.24×106 vs 4.81×107, p<0.0001). But it led to an notably expansion in HSC number (LT-HSC:1.18×105 v 8.59×103, p=0.0035) which had a same tendency as the phenotype of primary mice. Based on Ki67 and DAPI staining, proportion of HSCs in G1 phase increased (59.85% vs 38.63%, p=0.0007), while that in G0 (33.58% vs 44.2%, p=0.045) and S/G2/M (4.86% vs 13.41%, p=0.0002) phases decreased. These results implied that AML1-ETO induction could reduce the quiescence and self-renewal ability of HSCs obviously in comparison with normal HSCs. Bulk RNA sequencing was performed in LT-HSCs and GMPs sorted from both groups. Genesets related to cell proliferation, cell cycle regulation and Myc targets were enriched in LT-HSCs from control group. It was also found that genesets of tricarboxylic acid (TCA) cycle, glycolysis and fatty acid metabolism were enriched in LT-HSCs from control group. To validate it, Seahorse extracellular flux assay was performed to evaluate oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) on HSPC population (c-kitenriched cells). We found that OCR and ECAR both decreased significantly in AEKI group that supported the results from RNA-seq. RNA-seq data also showed that fatty acid metabolic pathway was enriched in AEKI group during the process from LT-HSCs to GMPs, which suggested that AEKI HSPCs maintained abnormal function through excessive fatty acid supply while it was not necessary during normal hematopoiesis. To confirm the above speculation, the mice were fed with fat-free or normal food after the AML-ETO induction in vivo to evaluate the impact of fatty acid on hematopoiesis. Interestingly, BM chimerism increased on the fat-free group (31.56% vs 15.68%, p=0.013), with the absolute number of LT-HSCs (5.16×105 vs 1.80×106, p=0.068), ST-HSCs (1.28×106 vs 2.72×106, p=0.026) and MPPs (4.70×104 vs 2.53×105, p=0.013) reduced obviously compared with in a normal diet. It suggested the excessive accumulation of HSCs was partly recovered. In summary, our study suggested that AML1-ETO induction could cause HSCs to lose self-renewal potential and lead to differentiation disruption during the pre-leukemic stage of AML. Limiting exogenous lipid uptake was able to rescue the phenotype of differentiation disrupt of HSPCs partly and it could be a promising therapeutic strategy.

Effect of different types of oil intake on the blood index and the intestinal flora of rats.

Dietary fat is an important part of human diet and has a close relationship with human health. However, it is still unclear how gut microbiota in adolescent responds to dietary fats at a normal dose. In this study, fat-free group (BC) was used as blank control group, we explored blood index and gut microbiota structure in growing rat(aged 1 months) after feeding a normal dose of 16.9% stewed lard(SL), refined lard(RL), fish oil(FO) and soybean oil(SO) for 6 weeks, respectively. The results showed that compared with RL group, SL group showed reduced fasting blood sugar and blood lipid levels and improved nutrient absorption capacity of the intestine. The blood indexes of glucose (Glu), total cholesterol (TC) and total triglyceride (TG) in FO treatment group were relatively low. The abundance of Bacteroidetes in the BC group decreased, and the abundance of Firmicutes increased. The Firmicutes/Bacteroidetes ratio of the FO group was relatively low, and the Firmicutes/Bacteroidetes ratio of the SL group and the SO group was lower than that of the RL group. The abundance of Bacteroidaceae in the SL group was increased. Research results showed that fat-free diets will increase the risk of obesity to a certain extent; compared with refined lard, stewed lard, soybean oil and fish oil can reduce the risk of obesity to a certain extent. The present study could find that the addition and types of dietary fat will affect the abundance and diversity of rat intestinal flora, and provide some information for nutritional evaluation about these dietary lipids.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13568-022-01387-w.

Effects of soybean oil emulsion and eicosapentaenoic acid on stress response and immune function after a severely stressful operation.

To investigate the effects of soybean oil emulsion and oral or enteral administration of eicosapentaenoic acid (EPA) on stress response, cytokine production, protein metabolism, and immune function after surgery for esophageal cancer. It has been reported that safflower oil, rich in n-6 polyunsaturated fatty acid (n-6 PUFA), affects the survival rate of septic animals and decreases the immune function. It has also been reported that the administration of fish oil, in contrast, reduces these stress responses and stress-induced immunosuppression. In humans, the effects of soybean oil emulsion and the administration of EPA on stress response and immune function after surgery have not been established. Patients who underwent esophagectomy with thoracotomy were divided into three groups. Seven patients were fed by total parenteral nutrition (TPN) with soybean oil emulsion, which accounted for 20% of total calories. Seven patients were given oral or enteral administration of 1.8 g/day EPA, in addition to TPN with soybean oil emulsion. Nine patients served as the control group; these patients received fat-free TPN. Serum interleukin-6 (IL-6), C-reactive protein, concanavalin A (con A)- or phytohemagglutinin (PHA)-stimulated lymphocyte proliferation, natural killer cell activity, and stress hormones were measured. The postoperative level of serum IL-6 was significantly higher in the group receiving soybean oil emulsion than in the fat-free group. Oral or enteral supplementation of EPA with soybean oil emulsion significantly reduced the level of serum IL-6 compared with the patients receiving soybean oil emulsion. Con A- or PHA-stimulated lymphocyte proliferation decreased significantly on postoperative day 7 in all groups of patients. The supplementation of EPA with soybean oil emulsion significantly improved the lymphocyte proliferation and natural killer cell activity on postoperative day 21 compared with the group receiving soybean oil emulsion. Soybean oil emulsion amplifies, and the supplementation of EPA reduces, the stress response and stress-induced immunosuppression.

Regulation of hepatic cholesterol metabolism in the rat in vivo: effect of a synthetic fat-free diet on sterol synthesis and low-density lipoprotein transport.

A synthetic fat-free diet, previously shown to decrease hepatic cholesterol synthesis, was utilized to manipulate cholesterol balance in vivo in female Sprague-Dawley rats. A significant 65% decrease of hepatic cholesterol synthesis compared to controls was shown after 1 week of treatment, which remained constant during the following 3 weeks. The inhibitory effect of the diet was completely abolished by cholestyramine supplementation. At week 3 of the experimental diet, bile acid synthesis was reduced by 63%, this reduction being correlated with decreased recycling frequency of the bile acid pool. Hepatic clearance of low-density lipoprotein (LDL) was slightly decreased, with no changes in plasma cholesterol, hepatic LDL-cholesterol uptake and whole body LDL-cholesterol production. When cholesterol and saturated fatty acids were supplemented to the diets in the attempt to disclose alteration in LDL transport, LDL clearance was unaffected; plasma LDL-cholesterol and hepatic LDL-cholesterol uptake were increased, as a consequence of increased LDL-cholesterol production. On the other hand, hepatic cholesterol synthesis was further suppressed; bile acid synthesis was increased by cholesterol supplementation in the fat-free group, even if to subnormal levels. These findings suggest that: (1) bile acid synthesis is decreased by feeding a synthetic fat-free diet, probably due to slower recirculation of bile acids along the entero-hepatic axis in conditions of reduced functional need; (2) consequently, a significant reduction of hepatic cholesterol synthesis is observed with no changes in LDL-cholesterol uptake; (3) further supplementation of dietary cholesterol and saturated fats is compensated for by changes in the rates of cholesterol and bile acid synthesis, but not of LDL transport. The data confirm the existence of independent regulation for hepatic sterol synthesis and LDL transport in this species.

Chronical ingestion of oxidized oil in the rat: Effect on lipid composition and on cytidylyl transferase activity in various tissues

An oxidized oil with 370 mmol hydroperoxides by kg and 41% oxidized esters was mixed with a fat-free diet at a rate of 4%, alone or in equivalent weight with fresh oil, and given to rats for 4 weeks. The fat-free diet and a well-balanced food were used as references. The oxidized oil group had a one fourth reduction in the weight growth, superior to that of the fat-free group. In the stools, the concentration of the lipids was increased, with the presence of polar and high MW compounds in proportion to the ingested quantity of oxidized oil, which suggested an intestinal sorting out of the oxidized esters. For the oxidized oil and the fat-free groups, a liver steatosis was observed and, in their liver phospholipids, linoleic acid was reduced to one half, whereas monounsaturated FA were increased and eicosatrienoic acid reached respectively 3% and 14% against 1% in the control group. The cytidylyl transferase activity was increased in the 106000 g supernatant of the liver homogenates, linked to the monounsaturated FA variations. Arachidonic acid was conserved in the phospholipids of the oxidized oil group, with 29% in the liver against 26% and 12% for the control and the fat free groups, in consequence or a possible arachidonic acid preferential synthesis or of an eicosanoids biosynthesis clamping.

Modulation of the levels of cytochromes P450 in rat liver and lung by dietary lipid

This study was undertaken to investigate the effect of dietary lipid on the regulation of several constitutive P450 isozymes. Male Sprague-Dawley rats with body weights of 130–140 g were fed either a 20% corn oil (CO) diet or a fat-free (FF) diet for 4 days following 2 days of fasting. Using liver microsomes, the catalytic activities and immunochemically detectable protein levels of P450s 1A1 and 2, 2A1, 2B1 and 2, 2C11, 2E1, and 3A were determined. The microsomes from rats fed the 20% CO diet exhibited 2-fold higher levels in N-nitrosodimethylamine demethylase activity and P450 2E1 protein than those from rats fed the FF diet. the CO group also showed 2.5-fold higher levels in 6β-hydroxylation of testosterone and P450 3A protein than the FF group. In contrast, the CO diet did not affect the immunodetectable level of P450 2C11 protein and its catalytic activities such as benzphetamine demethylase activity and 2α-hydroxylation of testosterone. P450 1A1 was not detectable in either group, but 1A2 was 2.5-fold higher in the CO group than in the FF group. In the liver, the P450 2B1 level was very low in both groups as measured by pentoxyresorufin dealkylase activity and the protein level, whereas 2B2 was 2.5-fold higher in the CO diet group. In lung microsomes from rats fed different amounts of CO, an inverse relationship was observed between the P450 2B1 level and the dietary CO level. the results suggest that the constitutive levels of P450 isozymes are modulateted by dietary lipid in a selective manner; the levels of hepatic P450s 1A2, 2B2, 2E1, and 3A were regulated positively but the level of pulmonary P450 2B1 was suppressed by dietary lipid.

Comparison of the activity of the tryptophan-NAD pathway between rats fed a fat-free diet and a fat diet.

The effect of dietary fat on tryptophan-NAD metabolism was investigated. Weanling male rats of the Sprague Dawley strain were fed a 40% casein diet (nicotinic acid-free) with or without 20% fat for 13 days. Although the food intake in 13 days was significantly higher in the fat-free group than in the fat group, the gains in body weight in the two groups were almost the same, because of the same energy intakes. The urinary excretion of tryptophan metabolites such as quinolinic acid, niacin and N1-methylnicotinamide was greatly increased in the fat group in comparison with that in the fat-free group. The urinary excretion of xanthurenic acid was almost the same in the two groups. The blood NAD level of the fat group was significantly increased. The activities of liver amino-carboxymuconate-semialdehyde decarboxylase and liver nicotinamide methyltransferase in the fat group were significantly reduced, and that of liver NMN adenylyltransferase was significantly increased. The changes of these three enzymes could be advantageous for the increased formation of NAD from tryptophan. As a result, the feeding of a high fat diet to rats increased the formation of niacin and niacin-related compounds.

Adipose tissue cholesterol storage: the effect of essential fatty acid deficiency.

SummaryEssential fatty acid deficiency was induced in one group of rats by feeding a fat-free diet, and in another group by supplying hydrogenated coconut oil. All deficient animals had significantly reduced weight gain and tended to have decreased epididymal fat cell size compared to controls. Rats in the fat-free group had significantly more adipocyte free cholesterol than control animals, but no significant alteration in stored free sterol occurred in rats made essential fatty acid deficient with hydrogenated coconut oil. Between experimental essential fatty acid deficient groups, the fat-free group had greater quantities of adipocyte free, and hence, total cholesterol. No alterations in ester content due to essential fatty acid deficiency could be demonstrated, although the percentage of total cholesterol as esters decreased significantly in both experimental groups. It is suggested that adipose tissue responds differently than other peripheral tissues to essential fatty acid deficiency.

Influence of Dietary Fatty Acids on Liver and Adipose Tissue Lipogenesis and on Liver Metabolites in Meal-Fed Rats

Rats were trained to eat a fat-free high carbohydrate diet from 800 to 1100 hours each day. After adaptation to meal-eating, the fat- free diet was supplemented with 8% methyl stA©arate(Ci8;o) or 3% methyl linoleate (Ci8:2) for 7 days. Relative to the fat-free group, hepatic utiliza tion of acetate unit equivalents (C2 units) for fatty acid synthesis per mg soluble protein by the Ci8:o group was not significantly altered, whereas Ci8:2 supplementation significantly depressed hepatic fatty acid synthesis. Supplemental Ci8:2 also caused a significant decline in liver fatty acid synthetase and acetyl CoA carboxylase while fat-free and Ci8:o groups dis played similar enzyme activities. Within a treatment, C2 unit utilization tor in vivo fatty acid synthesis was identical to that of acetyl CoA car boxylase and fatty acid synthetase activities in vitro. Therefore, shortly after a meal, the hepatic activities of these two enzymes appear to be functioning at near capacity. Ci8:2 supplementation to the fat-free diet for 7 days caused a 25% decline in glucokinase and pyruvate kinase activ ities, but only pyruvate kinase was significantly depressed. In contrast, citrate cleavage enzyme and fatty acid synthetase were both significantly reduced in activity by 50%. Plasma unesterified fatty acid levels in rats fed Ci8:2 for 5 days were not significantly elevated prior to a meal, al though dietary Ci8:2 did cause a fourfold rise in plasma free linoleate. Quantitation of long chain acyl CoA esters in freeze-clamped liver tissue of rats fed fat-free or fat-free plus 3% Ci8:2 or Ci8:3 diets revealed no con centration differences between treatments either before or after a meal. Similarly, lactate and pyruvate concentrations as well as the lactate: pyru vate ratios were not significantly changed by dietary Ci8:2 or Ci8:3. The inhibitory effects of C18:2 or Ci8;3 appear not to be mediated through changes in total plasma free fatty acid levels, in total hepatic long chain acyl CoA concentration or in hepatic cytosolic redox state. J. Nutr. 107: 1277-1287, 1977.

Effect of fat intake on cholesterol turnover and bile acid formation.

Three groups of male rats were maintained on diets containing different amounts of fat. After one week on such regimens, they were injected intraperitoneally with cholesterol-3H. During the following 28 days, the radioactivity and quantity of fecal cholesterol and its metabolities were determined. The coprostanol excretion was the about same in all groups and the bile acids excretion increased with increasing fat intake; however, compared to the fat-free group, the excretion of the injected cholesterol-3H was greater in the 3% fat group and less in the 10% fat group. Consequently, the specific radioactivity of bile acids was lower in the 10% group than in the others. The half-life of labelled cholesterol was 12.6, 16.0 and 22.2 days for the 3%, 10% fat and fat-free groups, respectively. Rather than a fat-free diet, a low-fat diet of 3% or so, would be of more advantage in eliminating cholesterol by increasing the formation of bile acids to emulsify the fat. In the 10% fat group, however, the enlarged pool size of bile acid probably delayed cholesterol metabolism to bile acids.

Effect of feeding different levels of corn oil on the composition of submandibular salivary gland fatty acids in rats

Male, weanling rats were fed synthetic diets containing 0, 3, 10 and 20 per cent corn oil. Rats were killed after 3 weeks, their plasma and submandibular salivary glands were extracted for lipids, and the fatty acid composition was determined. There were significant changes in the fatty acid composition of both plasma and submandibular salivary glands as a result of feeding different levels of corn oil in the diet. The proportions of monoenoic fatty acids (16:1, 18:1) decreased whereas those of linoleic acid increased as the level of corn oil was increased from 0 to 20 per cent. Arachidonic acid level was the lowest in the fat-free group as compared with the other groups. Plasma and submandibular salivary gland lipids of rats fed 0 per cent corn oil in their diet contained another fatty acid which appears to be eicosadicnoic fatty acid. The changes in submandibular salivary gland fatty acids were correlated with the changes in plasma fatty acids. Fractions of neutral lipids and phospholipids which were isolated from the submandibular salivary glands showed changes in their fatty acid composition similar to those observed in the total lipid extract.

Experimental Studies on the Interrelationships of Nutrition and Physical Exercise

The combined effects of the quality of dietary fats, vitamin E (V. E) supplementation and physical exercise on the cholesterol contents and fatty acid composition of both in serum and tissue lipids, and also on urinary 17-ketosteroid (17-KS) excretion were investigated. Male rats at 40 days of age were allocated to either a fat-free diet or diets containing 20% of safflower oil or beef tallow with and without an additional supply of V. E (330mg/kg diet).Ten rats from each dietary group were housed in cages equipped with a revolving wheel inside and allowed voluntary exercise throughout the entire period. After 2 months on the experimental regimen, a significant drop in the serum cholesterol and a slight increased in liver cholesterol were observed among the animals given safflower oil. V. E supplementation exerted a reverse effect against safflower oil on lowering the serum cholesterol. The rats fed on beef tallow showed the least deposition of cholesterol in liver, followed by those of a fat-free group. Prolonged deprivation of fat from diets was accompanied by a high cholesterol content in the adrenals. Exercise had no appreciable effect on serum cholesterol levels. Dietary fat had a pronounced effect on the fatty acid composition of lipids in serum, liver, adrenal and perirenal fat depot. A marked reduction in linoleate and arachidonate and a compensatory increase in C20-trienes in the liver lipid of rats given a fat-free diet were seen. Both exercise and V. E had no effects on fatty acid composition. Prolonged ingestion of beef tallow resulted in a small depression of urinary 17-KS excretion, but exercise and V. E exerted no further influences on the 17-KS output.