Fish oil-containing lipid emulsions in patients with sepsis

Lipid Use in Hospitalized Adults Requiring Parenteral Nutrition

In hospitalized patients, lipid emulsions are an integral part of balanced parenteral nutrition. Traditionally, a single lipid source, soybean oil, has been given to patients and was usually regarded as just a source of energy and to prevent essential fatty-acid deficiency. However, mixtures of different lipid emulsions have now become widely available, including mixtures of soybean oil, medium-chain triglycerides, olive oil, and fish oil. Fish oil is high in the ω-3 polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). There is a growing body of evidence that these ω-3 fatty acids can exert beneficial immunomodulatory, anti-inflammatory, and inflammation-resolution effects across a wide range of patient groups including surgical, cancer, and critically ill patients. At least in part, these effects are realized via potent specialized pro-resolution mediators (SPMs). Moreover, parenteral nutrition including ω-3 fatty acids can result in additional clinical benefits over the use of standard lipid emulsions, such as reductions in infection rates and length of hospital and intensive care unit stay. Clinical and experimental evidence is reviewed regarding lipid emulsion use in a variety of hospitalized patient groups, including surgical, critically ill, sepsis, trauma, and acute pancreatitis patients. Practical aspects of lipid emulsion use in critically ill patients are also considered, such as how to determine and fulfill energy expenditure, how and when to consider parenteral nutrition, duration of infusion, and safety monitoring.

Oral delivery of fish oil in oil-in-water nanoemulsion: development, colloidal stability and modulatory effect on in vivo inflammatory induction in mice

To improve the oral absorption of fish oil and test its anti-inflammatory effect, a fish oil nanoemulsion was developed using cis-4,7,10,13,16,19-docosahexaenoic fatty acid as a biomarker for oral administration. The colloidal stability tests of the fish oil nanoemulsion showed an average size of 155.44 nm ± 6.46 (4 °C); 163.04 nm ± 9.97 (25 °C) and polydispersity index 0.22 ± 0.02 (4 °C), 0.21 ± 0.02 (25 °C), indicating systems with low polydispersity and stable droplets. The fish oil nanoemulsion did not alter the cell viability of the RAW 264.7 macrophages and, at a concentration of 0.024 mg/mL, was kinetically incorporated into the cells after 18 h of contact. The nanoemulsion was maintained in the gastrointestinal region for a significantly shorter period of time (p ≤ 0.05) compared to the intake of fish oil in free form. Inflammatory tests demonstrated that nanoemulsion and fish oil showed less (p ≤ 0.05) neutrophil infiltration after 24h of sepsis induction and there was a significant reduction (p ≤ 0.05) in the volume of paw edema in female adult Balb/c mice who received the nanoemulsion diet compared to the other experimental groups (control, formalin, fish oil and sunflower oil). These results indicate that the fish oil nanoemulsion was significantly effective in the dietary conditions tested here, presenting satisfactory responses in the modulation of inflammatory disorders, demonstrating interesting and beneficial nutraceutical effects.

Immunomodulation by an Omega-6 Fatty Acid Reduced Mixed Lipid Emulsion in Murine Acute Respiratory Distress Syndrome

Background: Acute respiratory distress syndrome (ARDS) is associated with both high morbidity and mortality in intensive care units worldwide. Patients with ARDS often require parenteral nutrition with lipid emulsions as essential components. In the present study, we assessed the immunomodulatory and apoptotic effects of a modern, n-6-reduced lipid emulsion mixture in murine ARDS. Methods: Mice received an infusion of either normal saline solution, pure long-chain triglyceride (LCT) emulsion, or SMOF (soybean oil, medium-chain triglycerides, olive oil, and fish oil) before a lipopolysaccharide (LPS) challenge. Mice were sacrificed at different time points (0, 24, or 72 h) after ARDS induction, and an analysis of inflammatory cytokines, protein concentrations, and the cellular composition of the alveolar and interstitial compartments was performed with special focus on alveolar apoptosis and necrosis. Results: Mice infused with SMOF showed decreased leukocyte invasion, protein leakage, myeloperoxidase activity, and cytokine production in alveolar spaces after LPS challenge compared to animals that received LCT. There were fewer cells in the lung interstitium of the SMOF group compared to the LCT group. Both lipid emulsions exerted pro-apoptotic and pro-necrotic properties on alveolar immune cells, with significantly increased necrosis in mice infused with LCT compared to SMOF. Conclusion: SMOF has both anti-inflammatory and pro-resolving influences in murine ARDS. Partial replacement of n-6 fatty acids with n-3/n-9 fatty acids may therefore benefit critically ill patients at risk for ARDS who require parenteral nutrition.

Omega-3 fatty acids modulate neonatal cytokine response to endotoxin

Neonatal immune response is characterized by an uncompensated pro-inflammatory response that can lead to inflammation-related morbidity and increased susceptibility to infection. We investigated the effects of long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) pre-treatment on cytokine secretion to low-concentration endotoxin (lipopolysaccharide, LPS) in THP-1 monocytes and neonatal cord blood (CB) from healthy full-term infants. Pre-treatment of THP-1 cells, with either n-3 PUFA at 25 or 100 μM significantly reduced IL-6, IL-10, and IL-12 secretion while DHA, but not EPA, reduced TNF-α response to LPS. DHA inhibition was stronger compared to EPA and effective at the low concentration. The same concentrations of n-3 PUFAs inhibited IL-12 but not IL-10 cytokine response in whole CB from 9 infants pre-treated for 24 h. To assess clinical relevance for acute response to LPS, the effects of low-concentration DHA at 25 μM or 12.5 μM were assessed before and after LPS exposure of isolated CB mononuclear cells from 20 infants for 1 h. When added before or after LPS, physiologic DHA treatment produced significant concentration-dependent inhibition of TNF-α, IL-6, IL-1β, and IL-8 secretion. The results demonstrate prophylactic and therapeutic modulation of neonatal cytokine response to LPS and provide proof-of-concept that low-concentration administration of n-3 PUFA could attenuate or resolve neonatal inflammatory response.

Use of n-3 PUFAs can decrease the mortality in patients with systemic inflammatory response syndrome: a systematic review and meta-analysis

BACKGROUND

There have been several meta-analyses evaluating the effect of n-3 polyunsaturated fatty acids (PUFAs) in critically ill patients, but of these, none focused on patients with systemic inflammatory response syndrome (SIRS). The objective of this meta-analysis was to evaluate the effect of omega-3 fatty acids (n-3 FAs) on this narrow subset.

METHODS

All relevant articles were searched on MEDLINE, EMBASE, SpringerLink, and the Cochrane Database of Systematic Reviews from 1990 to 2014. Meta-analyses were used to evaluate risk ratios and mean differences with 95% confidence intervals between the n-3 PUFA group and the control group. Subgroup analyses were conducted in terms of the route of fish oil.

RESULTS

Nine randomized controlled trials (RCTs) with 783 adult patients were included in this study. Compared with control groups, n-3 FA provision can significantly reduce the incidence of mortality (RR: 0.77 [0.60, 0.97]; P=0.03; I2=0%). Secondary outcomes showed no significant differences between groups except for shorter length of hospital stay (weighted mean difference: -10.56 [-19.76, -1.36], p<0.00001, I2=99%).

CONCLUSIONS

Overall, this meta-analysis from RCTs indicates that provision of n-3 PUFAs has a therapeutic effect on survival rate in patients with SIRS.

Impact of short- and medium-chain fatty acids on mitochondrial function in severe inflammation

BACKGROUND

Sepsis is a severe inflammatory disorder with a high mortality in intensive care units mostly due to multiorgan failure. Mitochondrial dysfunction is regarded as a key factor involved in the pathogenesis of septic disorders, leading to a decline in energy supply. The aim of the present study was to evaluate whether application of short-chain fatty acids (SCFAs) and medium-chain fatty acids (MCFAs) could improve mitochondrial function and thus might serve as a potential energy source under inflammatory conditions.

MATERIALS AND METHODS

As an experimental approach, starved human endothelial cells and monocytes were incubated with hexanoic acid, heptanoic acid, octanoic acid, or glucose and subsequently subjected to high-resolution respirometry to assess mitochondrial function under baseline conditions. In a second set of experiments, cells were pretreated with tumor necrosis factor-α to mimic inflammation and sepsis.

RESULTS

We demonstrated that addition of SCFAs and MCFAs increases mitochondrial respiratory capacity at baseline and inflammatory conditions in both cell types. None of the fatty acids induced changes in mitochondrial DNA content or the generation of proinflammatory cytokines, indicating a beneficial safety profile.

CONCLUSION

We deduce that SCFAs and MCFAs are suitable and safe sources of energy under inflammatory conditions with the capability to partly restore mitochondrial respiration.

Fatty acids as biocompounds: their role in human metabolism, health and disease: a review. part 2: fatty acid physiological roles and applications in human health and disease

BACKGROUND

This is the second of two review parts aiming at describing the major physiological roles of fatty acids, as well as their applications in specific conditions related to human health.

RESULTS

The review included the current literature published in Pubmed up to March 2011. In humans, fatty acids are a principle energy substrate and structural components of cell membranes (phospholipids) and second messengers. Fatty acids are also ligands of nuclear receptors affecting gene expression. Longer-chain (LC) polyunsaturated fatty acids (PUFA), including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid are precursors of lipid mediators such as eicosanoids (prostaglandins, leukotrienes, thromboxanes), resolvins and neuroprotectins. Lipid mediators produced by EPA and DHA (LC n-3 PUFA; mainly found in oily fish) are considered as inflammation-resolving, and thus, fish oil has been characterised as antiinflammatory. Recommendations for EPA plus DHA intake from oily fish vary between 250-450 mg/day. Dietary reference values for fat vary between nutrition bodies, but mainly agree on a low total and saturated fat intake. The existing literature supports the protective effects of LC n-3 PUFA (as opposed to n-6 PUFA and saturated fat) in maternal and offspring health, cardiovascular health, insulin sensitivity, the metabolic syndrome, cancer, critically ill patients, and immune system disorders.

CONCLUSION

Fatty acids are involved in multiple pathways and play a major role in health. Further investigation and a nutrigenomics approach to the effects of these biocompounds on health and disease development are imperative and highlight the importance of environmental modifications on disease outcome.