Immune modulation by parenteral lipid emulsions
Department of Gastroenterology and Hepatology, Radboud University Nijmegen Medical Centre, Nijmegen, Netherlands. American Journal of Clinical Nutrition
(Impact Factor: 6.77).
Total parenteral nutrition is the final option for nutritional support of patients with severe intestinal failure. Lipid emulsions constitute the main source of fuel calories and fatty acids (FAs) in parenteral nutrition formulations. However, adverse effects on patient outcomes have been attributed to the use of lipids, mostly in relation to impaired immune defenses and altered inflammatory responses. Over the years, this issue has remained in the limelight, also because technical advances have provided no safeguard against the most daunting problems, ie, infectious complications. Nevertheless, numerous investigations have failed to produce a clear picture of the immunologic characteristics of the most commonly used soybean oil-derived lipid emulsions, although their high content of n-6 polyunsaturated FAs (PUFAs) has been considered a drawback because of their proinflammatory potential. This concern initiated the development of emulsions in which part of the n-6 FA component is replaced by less bioactive FAs, such as coconut oil (rich in medium-chain saturated FAs) or olive oil (rich in the n-9 monounsaturated FA oleic acid). Another approach has been to use fish oil (rich in n-3 PUFA), the FAs of which have biological activities different from those of n-6 PUFAs. Recent studies on the modulation of host defenses and inflammation by fish-oil emulsions have yielded consistent data, which indicate that these emulsions may provide a tool to beneficially alter the course of immune-mediated conditions. Although most of these lipids have not yet become available on the US market, this review synthesizes available information on immunologic characteristics of the different lipids that currently can be applied via parenteral nutrition support.
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- "HQ estimated effects, incremental and subgroup. Lipids are an essential component of PN, not only as an energy-dense source of calories 51 within PN formulations but also due to their important metabolic and functional properties, e.g.emulsions represent possible alternatives[4,2].esterified at random, resulting in the formation of mixed triglyceride molecules with both medium- 74 chain and long-chain fatty acids bound to the same glycerol backbone[6,8]. "
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New generations of parenteral lipid emulsions combine Long Chain Triglycerides (LCTs) with Medium Chain Triglycerides (MCTs) either by physically mixing MCT- and LCT-containing oils or by using synthetically structured triglycerides (STGs). In order to clarify some open issues relating to their comparative effect, in particular in terms of clinical outcomes, pertinent evidence was systematically identified, reviewed and meta-analyzed.
PubMed, Scopus, Wanfang Data, China Hospital Knowledge Database and Google Scholar were searched for published clinical trials comparing STGs vs. MCTs/LCTs PN regimens administered over 5-7 days in surgical and/or critically ill patients. Two independent investigators performed screening and data extraction using a predefined list of parameters. Data were pooled using RevMan(®) 5.2. Quality of evidence was assessed according to Cochrane's risk of bias tool. Pre-specified high quality (HQ), incremental analyses and a post hoc subgroup analysis were performed.
21 studies were included. The meta-analysis revealed a significantly better cumulative nitrogen balance (Std. mean difference [95% CI]) (1.34 [0.98-1.7], p < 0.00001), as well as higher values for pre-albumin (24.99 mg/L [6.71-43.27], p < 0.000001), and albumin (1.22 g/L [0.66-1.77] p < 0.0001), while plasma triglycerides were significantly lower (-0.28 mmol/L [-0.41 to -0.15], p < 0.0001) in the STG vs. MCT/LCT group. ALT, AST, and GGT were significantly lower with STGs than with MCTs/LCTs, while for total bilirubin and ALP only a trend was observed. STGs were also associated with a trend to a shorter hospital length of stay (LOS) (-1.74 days [-3.49 to 0.01] p = 0.05). Quality of evidence was affected by an unclear risk of selection bias, mostly due to the lack of detailed reporting (random sequence generation, allocation concealment). For the other domains, most of the weighted information was judged at low risk of bias. HQ estimated effects, incremental and subgroup analyses were consistent with the main analysis.
In postsurgical and/or critically ill patients, the administration of STGs vs. MCT/LCTs was significantly associated with improved protein economy, better liver tolerance and a more efficient triglyceride elimination. With regard to clinical outcomes a strong trend towards reduced LOS was observed for STG patients.
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- "Chronic low-grade inflammation underlies the pathology of most metabolic disorders, and free n-3 PUFA has been shown to possess potent anti-inflammatory properties . N-3 PUFA alleviates inflammation by directly regulating transcription factors involved in inflammation [59-61] and indirectly by producing series-3 and series-5 eicosanoids [62,63]. In addition to their inflammation resolving properties, free unesterified n-3 PUFA have also been shown to improve symptoms of dyslipidaemia [9-11]. "
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ABSTRACT: Omega (n)-3 polyunsaturated fatty acids (PUFA) are converted to bioactive lipid components that are important mediators in metabolic and physiological pathways; however, which bioactive compounds are metabolically active, and their mechanisms of action are still not clear. We investigated using lipidomic techniques, the effects of diets high in n-3 PUFA on the fatty acid composition of various bioactive lipids in plasma and liver.
Female C57BL/6 mice were fed semi-purified diets (20% w/w fat) containing varying amounts of n-3 PUFA before mating, during gestation and lactation, and until weaning. Male offspring were continued on their mothers' diets for 16 weeks. Hepatic and plasma lipids were extracted in the presence of non-naturally occurring internal standards, and tandem electrospray ionization mass spectrometry methods were used to measure the fatty acyl compositions. There was no significant difference in total concentrations of phospholipids in both groups. However, there was a significantly higher concentration of eicosapentaenoic acid containing phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and cholesteryl esters (CE) (p < 0.01) in the high n-3 PUFA group compared to the low n-3 PUFA group in both liver and plasma. Plasma and liver from the high n-3 PUFA group also had a higher concentration of free n-3 PUFA (p < 0.05). There were no significant differences in plasma concentrations of different fatty acyl species of phosphatidylethanolamine, triglycerides, sphingomyelin and ceramides.
Our findings reveal for the first time that a diet high in n-3 PUFA caused enrichment of n-3 PUFA in PC, LPC, CE and free fatty acids in the plasma and liver of C57BL/6 mice. PC, LPC, and unesterified free n-3 PUFA are important bioactive lipids, thus altering their fatty acyl composition will have important metabolic and physiological roles.
Available from: Getty Huisman-de Waal
- "The nature of the underlying disease leading to intestinal failure may increase the risk of CRBSI. Also factors that are related to the composition of the parenteral nutrition formulation, such as caloric content and the presence of a lipid emulsion play a role, as well as the frequency and duration of the use of the venous access device. The presence of a venous access device that bypasses the natural host barriers by directly connecting the external environment to the patients' central bloodstream, has been identified as an independent risk factor for the occurrence of CRBSIs. "
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