The omega-6 arachidonic fatty acid, but not the omega-3 fatty acids, inhibits osteoblastogenesis and induces adipogenesis of human mesenchymal stem cells: potential implication in osteoporosis

Summary

Arachidonic fatty acid (AA) induces adipogenesis in human mesenchymal stem cells cultures, and high concentrations inhibit osteoblastogenesis; whereas eicosapentaenoic and docosahexaenoic fatty acids do not induce adipogenesis and do not inhibit osteoblastogenesis. In mesenchymal stem cells, omega-6 arachidonic polyunsaturated fatty acid promotes the differentiation of adipocytes and inhibits the osteoblast differentiation. While omega-3 fatty acids do not affect the adipogenic differentiation their effects on osteoblastogenesis are less relevant. An increased ratio of omega-3/omega-6 fatty acid consumption can prevent bone mass loss.

Introduction

Consumption of omega-3 may protect against osteoporosis since they may inhibit osteoclastogenesis. However, with aging, MSC in bone marrow are increasingly differentiated into adipocytes, reducing the number of osteoblasts. Products derived from omega-6 and omega-3 metabolism may affect MSC differentiation into osteoblasts and adipocytes.

Methods

Human MSC have been differentiated into osteoblasts or adipocytes in the presence of omega-6 (AA), or omega-3 (DHA and EPA), and osteoblastic and adipocytic markers have been analyzed.

Results

AA decreases the expression of osteogenic markers and the osteoprotegerin/receptor activator of nuclear factor kappa β ligand gene expression ratio (opg/rankl). High concentrations of AA inhibit the mineralization and cause the appearance of adipocytes in MSC differentiating into osteoblasts to a higher extent than DHA or EPA. In MSC differentiated into adipocytes, AA increases adipogenesis, while DHA and EPA do not affect it. AA caused the appearance of adipocytes in undifferentiated MSC. The lipoxygenase gene (alox15b) is induced by omega-3 in MSC induced to osteoblasts, and by omega-6 in MSC induced to adipocytes.

Conclusions

An increase in the intake of omega-3 respect to omega-6 may provide protection against the loss of bone mass, since omega-6 favors the osteoclastic activity by diminishing the opg/rankl gene expression in osteoblasts and promotes MSC differentiation into adipocytes, thus diminishing the production of osteoblasts.     

Dietary omega-3 fatty acids decrease mortality and Kupffer cell prostaglandin E2 production in a rat model of chronic sepsis

We tested the hypothesis that substitution of omega-3 fat for dietary omega-6 fat would reduce mortality and decrease Kupffer cell prostaglandin E2 (PGE2) production in a rat model of chronic sepsis. Rats were fed via gastrostomy for 12 days with isonitrogenous, isocaloric diets containing 15% of calories as either safflower oil (omega-6) or a 10:1 mixture of menhaden oil (omega-3) and safflower oil. After five days of feeding, animals received an intra-abdominal abscess of defined bacterial content. Survivors were killed on post-laparotomy day 6 in conjunction with liver perfusion and protease liver digestion for Kupffer cell isolation. Kupffer cell PGE2 production was measured by radioimmunoassay after 18 hours of cell culture and again after stimulation with 0 LPS, 10 ng/ml LPS, and 10 micrograms/LPS. Mortality was decreased in menhaden oil-fed animals compared with safflower oil-fed animals (16% vs. 35%). Kupffer cell PGE2 production was decreased in menhaden oil-fed animals at 18 hours (354 +/- 54 vs. 570 +/- 95 pg/0.1 ml; p = 0.09) and after stimulation with 10 micrograms/ml LPS (140 +/- 41 vs. 288 +/- 45 pg/0.1 ml; p = 0.03) compared with safflower oil-fed animals.     

Effects of omega-3 fatty acids on acute necrotizing pancreatitis in rats

The aim of this study was to investigate the influence of omega-3 fatty acids (omega3FA) on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. The induction of ANP resulted in significant increases in mortality rate, intestinal permeability, bacterial infection in pancreas and extrapancreatic organs, and serum activity of urea and amylase, alanine transferase (ALT), interleukin (IL)-6, tumor necrotizing factor-alpha (TNF-alpha), lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in the pancreas and lung, and a considerable decrease of concentrations of calcium, protein and albumin. The use of omega3FA reduced mortality, phenol sulfophthalein excretion in urine, bacterial infection in pancreas, liver, spleen, MPO and MDA levels in pancreatic and lung tissue, LDH level in BAL fluid and serum IL-6 and TNF-alpha values. Serum triglyceride increased only in the omega3FA groups. Serum amylase, ALT, calcium, urea, protein, IL-1, and degree of pancreatic damage indicated no difference between the pancreatitis groups. Increased intestinal permeability and cytokine levels, and free radical damage play an important role during the course of acute pancreatitis. The treatment with omega3FA improves these effects. omega3FA may be useful in the treatment during ANP in rats. Therefore, it can be beneficial in patients with pancreatitis.     

Reduction of hepatocellular injury after common bile duct ligation using omega-3 fatty acids

Purpose

Bile duct obstruction and subsequent cholestasis produces hepatocellular injury and an inflammatory response. Fatty acid constitution of cell membranes plays a major role in the inflammatory cascade. Omega-3 fatty acids are antiinflammatory. We proposed that omega-3 fatty acid supplementation would reduce hepatocellular damage and cell death in a model of murine common bile duct ligation.

Methods

Mice underwent bile duct ligation and were administered either control soy diet (omega-6) or Menhaden diet (omega-3), and parameters of liver injury were measured at postoperative days 1, 4, and 8. Serum was analyzed for liver function tests. Liver tissue was scored for histologic necrosis and inflammation, and apoptosis was qualitatively measured.

Results

At day 8, comparing control and Menhaden, liver function tests were not significantly different. The H&E slides were analyzed and scored. At day 4, the mean necrosis scores for the Menhaden-fed group was 0.01 ± 0.028 and 0.46 ± 0.108 for the soy-fed group (P = .001) and at day 8, 0.420 ± 0.107 and 1.22 ± 0.132 (P < .001). The mean portal inflammation score for day 4 Menhaden-fed and soy-fed mice was 1.40 ± 0.245 for both groups (P = 1.00) and for day 8, 1.80 ± 0.200 and 2.80 ± 0.200 (P = .008). At day 1, the median terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling scores of the Menhaden vs soy group were 6.0 and 0.0 (P < .001); day 4, 24.0 and 3.0 (P < .001); and day 8, 0.0 and 3.0 (P < .001), respectively.

Conclusion

Although there appears to be a trend toward biochemical protection and a marked reduction of necrosis and inflammation, there was no significant liver function test difference between control and Menhaden groups. Considering our data of blunted histologic hepatotoxicity with omega-3 fatty acid supplementation, we hypothesize that this may be a method of reducing long-term complications of liver injury secondary to diseases of cholestasis such as biliary atresia, namely fibrosis and cirrhosis.     

Plasma fatty acid composition in continuous ambulatory peritoneal dialysis patients: an increased omega-6/omega-3 ratio and deficiency of essential fatty acids

Patients with end-stage renal disease, including those treated with peritoneal dialysis, have a high risk for death, particularly from cardiovascular causes. Plasma fatty acid (FA) composition is used as an indicator of disease risk, because its alteration has been related to metabolic disease and cardiovascular disease. For this purpose, we have measured plasma FA composition in continuous ambulatory peritoneal dialysis (CAPD) patients and compared them with those of healthy subjects. This study was performed on 51 (21 M, 30 F) CAPD patients at least 6 months under dialysis, aged 20-75 years (mean 47.81 ± 11.8 years) and 45 (25 M, 20 F) healthy control subjects aged 20-60 years (mean 38.62 ± 12.9 years). Plasma 10-cis-pentadecanoic acid, 10-cis-heptadecanoic acid, heneicosanoic acid, tricosanoic acid, nervonic acid, saturated fatty acid, and monounsaturated FA levels and delta 9 desaturase activity were significantly higher whereas linoleic acid, linolenic acid, 11,14-eicosedienoic acid, arachidonic acid, docosahexaenoic acid, and omega-3 FA levels were significantly lower in the CAPD group than those in the healthy group. Our results show that there are FA abnormalities and especially a depletion in essential FA levels and a high level of omega-6/omega-3 ratio in CAPD patients, the underlying mechanism of which is not known and needs to be investigated. Therefore, we believe that essential FA supplementation should be encouraged for CAPD patients.     

Results of a long-term administration of omega-3 fatty acids in haemodialysis patients with dyslipoproteinaemia

In this study we evaluated the effect of a daily administration of 1 g salmon-oil concentrate containing 0.2 g eicosapentaenoic acid (EPA) on the blood pressure, serum cholesterol, HDL and LDL cholesterol, triglycerides and magnesium of ten patients on chronic haemodialysis. Systolic and diastolic blood pressure values decreased significantly from 156 +/- 27.7/84 +/- 14.3 to 140 +/- 22.8/75.6 +/- 8.21 mmHg. Concordantly, mean arterial pressure (MAP) decreased significantly from 108 to 96 mmHg. Total serum cholesterol decreased significantly by 64%, HDL cholesterol increased by 47% (P less than 0.001). Serum triglyceride values decreased significantly to 48%. There was a distinct decline of magnesium from 1.42 +/- 0.27 to 1.28 +/- 0.13 mg/dl (P less than 0.001). According to these results, the administration of omega-3 fatty acids may be considered as a reasonable approach in the treatment of dyslipoproteinaemia in patients on continuous haemodialysis.     

Short-term administration of omega-3 fatty acids in hemodialysis patients with balanced lipid metabolism.

BACKGROUND: At present, it is discussed whether omega-3 fatty acids show anti-inflammatory, antithrombogenic, and antiatherosclerotic effects, also in patients with chronic renal failure. METHODS: In this prospective study, 11 hemodialysis (HD) patients, ages 59 +/- 17 years, who had balanced lipid metabolism and had been on HD for 53 +/- 47 months, were treated with a moderate dose of omega-3 fatty acids (1.2 g/day combined with 11.2 g/day pectin) for 12 weeks. Serum concentrations of c-reactive protein, homocysteine (Hcy), lipids, complement factors, blood gas analyses, 24-hour blood pressure, heart rate variability, electrocardiography, shunt blood flow, and recirculation, as well as peripheral oxygen saturation at the hand and foot, were measured at the start (t0w), and after 12 weeks (t12w) of therapy. Results Several assessed cardiovascular risk factors were significantly influenced. Levels of very-low-density lipoproteins (t0w, 77 +/- 26; t12w, 63 +/- 32 mg/dL; P <.05) and triglycerides (t0w, 261 +/- 157; t12w, 228 +/- 131 mg/dL; P =.068) were decreased. However, Hcy concentrations increased from 35.5 +/- 32.5 to 43.5 +/- 36.7 micromol/L ( P <.01) after 12 weeks. Anti-inflammatory and investigated clinical parameters did not significantly change during the study period. CONCLUSION: Limited positive effects on metabolic parameters were evaluated by short-term administration of omega-3 fatty acids in HD patients. Based on previous studies and on suspicion of atherosclerotic disorder in examined HD patients, we suppose that only high doses of omega-3 fatty acids given for a longer time influence inflammation and atherosclerosis.     

Gallic acid and omega-3 fatty acids mitigate epididymal and testicular toxicity in manganese-treated rats

Environmental contamination by manganese is correlated with diverse health outcomes plus reproductive dysfunction. Dietary gallic acid (GA) and omega-3 fatty acids (ω-3-FA) are well reported to elicit beneficial health effects. Though, information on GA and ω-3-FA effects on manganese-induced reproductive toxicity is absent in literature. We examined the effect of GA or ω-3-FA on manganese-induced epididymal and testicular toxicity in rats, exposed to manganese (15 mg/kg b.w.) alone, in combination with GA (30 mg/kg b.w.) or ω-3-FA (20 mg/kg b.w.) by gavage for 14 consecutive days. GA or ω-3-FA significantly (p < .05) prevented manganese-mediated increase in lipid peroxidation, myeloperoxidase activity, reactive oxygen and nitrogen species production but increased antioxidant enzymes activities and glutathione level in epididymis and testes treated rats. GA or ω-3-FA enhanced the activities of testicular function marker enzymes, namely acid phosphatase (ACP), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and glucose-6-phosphate dehydrogenase (G6PD) in the treated rats. GA or ω-3-FA amelioration of manganese-induced decreases in follicle-stimulating hormone, luteinising hormone, and testosterone levels were complemented by increase (p < .05) sperm functional characteristics in treated rats. Conclusively, GA or ω-3-FA may serve as dietary supplements to improve male reproductive dysfunction associated with manganese toxicity.     

Dietary omega-3 fatty acids may be associated with increased neuropathic pain in nerve-injured rats

Certain dietary proteins and oils are capable of decreasing chronic neuropathic pain levels in rats after partial sciatic nerve ligation injury. We tested, for the first time, the role of dietary polyunsaturated fatty acids in suppressing pain in partial sciatic nerve ligation-injured rats. Six groups of male Wistar rats were fed an identical casein-based, fat-free diet for 1 wk preceding partial sciatic nerve ligation injury and for 1 wk thereafter. In addition, rats received, via gavage, 1 mL/day of pure canola, corn, hemp, soy, or sunflower oil, differing significantly in their omega-3 and omega-6 polyunsaturated fatty acid content, or 1 mL of plain water. Responses to tactile and noxious heat stimuli were recorded before and after surgery and a difference score was calculated for each group by subtracting the preoperative from the post-partial sciatic nerve ligation values. Heat hyperalgesia, but not tactile allodynia, was significantly different among the dietary groups (P = 0.005). Heat hyperalgesia of rats fed hemp oil, developing the most robust response, was significantly larger compared with rats fed corn oil, developing the least pain model (difference score: 24.3 +/- 4.1 s versus 6.1 +/- 3.1 s, respectively; P < 0.001). These oils contain similar levels of omega-6 polyunsaturated fatty acids (hemp, 60%; corn, 58%) but their omega-3 levels are 28-fold different (20% versus 0.7%, respectively). A significant correlation was found among dietary levels of omega-3, but not omega-6 or the omega-3/omega-6 ratio, of the six dietary groups and heat hyperalgesia (P = 0.006). We conclude that dietary oil might predict levels of neuropathic pain in rats and that this effect may be associated with dietary omega-3 levels. IMPLICATIONS: We found that certain commonly used oils can have a significant analgesic effect in rats with persistent pain after partial nerve injury. This effect may be associated with the amounts of omega-3 fatty acids consumed by rats.     

The role of fish oil/omega-3 fatty acids in the treatment of IgA nephropathy

Beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) have been reported in recent epidemiologic studies and randomized clinical trials in a variety of cardiovascular and autoimmune diseases. Fish and marine oils are the most abundant and convenient sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the two major n-3 fatty acids that serve as substrates for cyclooxygenase and lipoxygenase pathways leading to less potent inflammatory mediators than those produced through the n-6 PUFA substrate, arachidonic acid. N-3 PUFA can also suppress inflammatory and/or immunologic responses through eicosanoid-independent mechanisms. Although the pathophysiology of IgA nephropathy is incompletely understood, it is likely that n-3 PUFA prevents renal disease progression by interfering with a number of effector pathways triggered by mesangial immune-complex deposition. In addition, potential targets of n-3 PUFA relevant to renal disease progression could be similar to those involved in preventing the development and progression of cardiovascular disease by lowering blood pressure, reducing serum lipid levels, decreasing vascular resistance, or preventing thrombosis. In IgA nephropathy, efficacy of n-3 PUFA contained in fish oil supplements has been tested with varying results. The largest randomized clinical trial performed by our collaborative group provided strong evidence that treatment for 2 years with a daily dose of 1.8 g of EPA and 1.2 g of DHA slowed the progression of renal disease in high-risk patients. These benefits persisted after 6.4 years of follow up. With safety, composition, and dosing convenience in mind, we can recommend two products that are available as pharmaceutical-grade fish-oil concentrates, Omacor (Pronova Biocare, Oslo, Norway) and Coromega (European Reference Botanical Laboratories, Carlsbad, CA).     

ω-3多不饱和脂肪酸诱导人胃癌细胞凋亡的实验研究

目的观察ω-3多不饱和脂肪酸(ω-3PUFAs)对SGC-7901人胃癌细胞系凋亡的影响并探究其机制。方法采用四甲基偶氮唑蓝(MTT)法、细胞形态学、DNA电泳和流式细胞技术对细胞生长与凋亡进行观察和分析,利用荧光探针rhodamine123检测线粒体跨膜电位,酶联免疫吸附法分析线粒体和胞质中细胞色素C的分布,气相色谱分析线粒体膜磷脂构成。结果二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)能显著抑制胃癌细胞的生长,诱发细胞凋亡,并呈现时间和剂量依赖性关系。40μg/mlEPA和DHA作用细胞24h后,线粒体跨膜电位显著降低(P<0.001),线粒体膜间细胞色素C大量释入胞质,EPA和DHA在线粒体膜磷脂构成中的比例迅速升高(P<0.001),而花生四烯酸(20:4ω-6,AA)占总磷脂的比例明显降低,由对照组的30.8%分别下降为20.9%和18.6%。结论ω-3PUFAs通过诱导细胞凋亡抑制胃癌细胞的生长,线粒体膜构成和功能的改变可能是ω-3PUFAs诱导凋亡的重要机制。     

A randomized trial of high-dose compared with low-dose omega-3 fatty acids in severe IgA nephropathy

Tested was the hypothesis that high-dose omega (omega)-3 fatty acids will be more effective than low-dose omega-3 fatty acids in preserving renal function in patients with severe IgA nephropathy in a randomized, open-label, parallel-group clinical trial. Patients were assigned to receive either high-dose fatty acids (EPA 3.76 g and DHA 2.94 g) or low-dose fatty acids (EPA 1.88 g and DHA 1.47 g), both given daily in a highly purified ethyl ester concentrate (Omacor). Patients were treated for a minimum of 2 yr in the absence of a treatment failure or until study closure (January 2000). Seventy-three patients were enrolled in the trial with two ranges of elevated serum creatinine (SC): 63 patients (86%) with a range of 1.5 to 2.9 mg/dl and 10 patients (14%) with a range of 3.0 to 4.9 mg/dl. The primary end point, within-patient rates of change in SC (2-yr minimum), showed an annualized median increase in SC of 0.08 mg/dl per yr in the low-dose group and 0.10 mg/dl per yr in the high-dose group (P: = 0.51). Patients in the lower entry SC range had lower SC slopes (P: = 0.02) and less end-stage renal disease (ESRD) (P: < 0.001) compared with those in the higher entry SC range. No patient died, and 18 patients developed ESRD: 10 in the low-dose group and 8 in the high-dose group (P: = 0.56). SC slopes were significantly lower, and survival free of ESRD was significantly higher (both, P: = 0.04) in the 63 Omacor-treated patients compared with the 22 placebo-treated patients from our previously reported clinical trial in which both groups had a similar level of renal impairment. Patient compliance was excellent, and no serious adverse events were noted. Low-dose and high-dose omega-3 fatty acids were similar in slowing the rate of renal function loss in high-risk patients with IgA nephropathy, particularly those with moderately advanced disease.     

Beneficial effect of omega-3 fatty acids on sirolimus- or everolimus-induced hypertriglyceridemia in heart transplant recipients

BACKGROUND: Hyperlipidemia is an important complication after organ transplantation and may contribute to the development of posttransplant-accelerated coronary artery disease. Immunosuppressive therapy, especially mammalian target of rapamycin inhibitors, induces a considerable increase in cholesterol and triglyceride plasma levels. Omega-3 fatty acids (FAs) exert cardioprotective effects supporting a therapeutic role in cardiovascular conditions. METHODS: An observational study of omega-3 FAs 4 g/day was performed in 15 heart transplant recipients with hypertriglyceridemia. Six patients received rapamycin, and nine received everolimus. Apart from one patient the immunosuppressive therapy was combined with mycophenolate mofetil, only one patient received steroids; two patients presented with diabetes. RESULTS: Mean triglyceride levels before heart transplantation (HTx) were 137+/-54 mg/dL. After HTx, before sirolimus or everolimus treatment triglyceride level had increased to 188+/-67 mg/dL (P<0.05). Treatment with sirolimus or everolimus induced an increase in triglycerides to 354+/-107 mg/dL (P<0.001). Subsequent treatment with omega-3 FAs for 4 months resulted in a marked decrease in triglycerides to 226+/-74 mg/dL (P<0.001). All patients (100%) showed a reduction in triglyceride by more than 20% (responders). In 10 of 15 patients available 12-month data confirmed the long-term efficacy of omega-3 FAs treatment. There were no adverse events or any discontinuations; no changes in immunosuppression were required. CONCLUSIONS: Treatment with mammalian target of rapamycin inhibitors after HTx induces marked increase in serum levels of triglycerides. Omega-3 FAs significantly lower triglyceride levels and seem to be effective, safe, and well-tolerated in sirolimus- or everolimus-treated heart transplant recipients.     

利多卡因抑制内皮细胞粘附因子表达进而抑制肝癌细胞粘附脐带静脉内皮细胞

【摘要】 目的 探讨利多卡因对血管内皮细胞粘附因子表达的影响。方法 采用不同浓度利多卡因预处理脐带静脉内皮细胞（HUVECs）30 min后,加入肿瘤坏死因子α（TNFα）进行刺激。通过实时荧光定量聚合酶链反应检测选择素E（CD62E）、血管细胞粘附分子-1（VCAM-1）和细胞间粘附分子-1（ICAM-1）表达量,蛋白免疫印迹分析NF-Kappa B（NF-κB）通路蛋白的改变,并通过细胞粘附实验评估利多卡因预处理对肝癌细胞（HepG2）粘附于HUVECs的影响。结果 利多卡因预处理可以明显抑制p65并抑制HepG2粘附于HUVECs。qRT-PCR结果表明利多卡因预处理可明显抑制TNF-α刺激后的CD62E、VCAM-1和ICAM-1表达水平的增高。结论 利多卡因可能通过抑制NF-κB通路进而抑制细胞粘附因子表达并抑制结肝癌细胞粘附于血管内皮细胞。