The effect of intralipid® on polymorphonuclear leucocytes

Health and Nutrition Status of the Caregiver: Effect on Caregiving Capacity

The importance of child care in ensuring optimal child survival, growth, and development is increasingly recognized. Unfortunately, poor health and nutrition status of the caregivers likely limit their agility to provide adequate care in many countries. Direct evidence for this has been shown in Egypt, where poor dietary intake, low haemoglobin levels, and low vitamin B6 status of the mothers were related to less time spent on care, less response to infants’ vocalization, less vocalization to infants, and greater utilization of older siblings as caregivers. In Kenya, lower maternal caloric intake was associated with less physical contact with their toddlers. Indirect evidence can be inferred from a review of illnesses affecting women globally in the light of the physical and mental demands of adequate caregiving. For this purpose, ill health of women is evaluated from both epidemiological and anthropological perspectives.

Immune modulation by parenteral lipid emulsions

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.

Effect of different lipid emulsions on the immunological function in humans: a systematic review with meta-analysis

BACKGROUND & AIMS

Reports regarding the pro- or anti-inflammatory effects of lipid emulsion used in parenteral nutrition are conflicting. Aim was to assess the effect of different intravenous lipid emulsions on immunological function in humans.

METHODS

We performed a computerized bibliographic search, searched reference lists in trial reports, hand-searched journals and contacted experts in the field. Randomized clinical trials evaluating the immunological effects of different parenteral lipid emulsions were included. Three authors independently performed data extraction, statistical processes were performed by two experts. Immunological parameters were classified by two immunologists as marker of improved or worsened immune function. A meta-analysis with standardized effect size estimation was performed for the comparison between long-chain triglycerides vs. glucose or other fat emulsions.

RESULTS

Of 682 assessed studies, 120 compared the immunological effects of intravenously applied lipid emulsions. Of 30 randomized trials, 14 were included in the meta-analysis. None of the lipid regimens showed any clear effect on the evolution of the immunological status or mortality in humans. Length of hospital stay and stay in the intensive care unit could not be evaluated.

CONCLUSION

We found no evidence that lipid emulsions and in particular those containing long-chain triglycerides have an unfavorable effect on immune function.

Oil-in-water lipid emulsions: implications for parenteral and ocular delivering systems

Lipid emulsions (LEs) are heterogenous dispersions of two immiscible liquids (oil-in-water or water-in-oil) and they are subjected to various instability processes like aggregation, flocculation, coalescence and hence eventual phase separation according to the second law of thermodynamics. However, the physical stability of the LE can substantially be improved with help of suitable emulsifiers that are capable of forming a mono- or multi-layer coating film around the dispersed liquid droplets in such a way to reduce interfacial tension or to increase droplet-droplet repulsion. Depending on the concentrations of these three components (oil-water-emulsifier) and the efficiency of the emulsification equipments used to reduce droplet size, the final LE may be in the form of oil-in-water (o/w), water-in-oil (w/o), micron, submicron and double or multiple emulsions (o/w/o and w/o/w). The o/w type LEs (LE) are colloidal drug carriers, which have various therapeutic applications. As an intravenous delivery system it incorporates lipophilic water non-soluble drugs, stabilize drugs that tend to undergo hydrolysis and reduce side effects of various potent drugs. When the LE is used as an ocular delivery systems they increase local bioavailability, sustain the pharmacological effect of drugs and decrease systemic side effects of the drugs. Thus, the rationale of using LE as an integral part of effective treatment is clear. Following administration of LE through these routes, the biofate of LE associated bioactive molecules are somehow related to the vehicles disposition kinetics inside blood or eyeball. However, the LE is not devoid from undergoing various bio-process while exerting their efficacious actions. The purpose of this review is therefore to give an implication of LE for parenteral and ocular delivering systems.

Tocopherol isoforms in parenteral lipid emulsions and neutrophil activation

BACKGROUND AND AIMS

Tocopherol is a lipid-soluble anti-oxidant that exists in several isoforms. Patients on total parenteral nutrition depend on lipid emulsions for their tocopherol intake. In the present study, we analysed the content of tocopherol isoforms in various lipid emulsions. We also tested the hypothesis that immune-modulating effects of lipid emulsions could be attributed to different concentrations of alpha-tocopherol (alpha-toc) or peroxidation products.

METHOD

alpha-, beta-, gamma- and delta-toc were measured in emulsions containing long-chain triglycerides (LCT), mixed long- and medium-chain triglycerides (LCT/MCT), structured lipids (SL), olive oil (OO) or fish oil (FO). As a measure for cellular activation, neutrophil membrane adhesion markers were assessed after exposure to two LCT/MCT emulsions that differ only in alpha-toc content.

RESULTS

Various emulsions differed widely in tocopherol contents, especially with respect to the alpha- isoform. The latter isomer also was subject to considerable degradation despite adequate storage conditions. The previously observed activation of neutrophils by LCT/MCT was not influenced by the increased concentration of alpha-toc or the decreased concentration of lipid peroxidation products in a new LCT/MCT emulsion.

CONCLUSIONS

Tocopherol supplementation by parenteral lipid emulsions strongly depends on the lipid source and the storage lifetime of the emulsion. The effects of LCT/MCT on the immune system are not modulated by alpha-toc or by lipid peroxidation products.

Parenteral lipid emulsions and phagocytic systems

Lipid emulsions (LE) for parenteral use are complex emulsions containing fatty acids, glycerol, phospholipids and tocopherol in variable amounts and concentrations. In clinical practice, LE have been employed for more than 30 years. Fatty acids may have different impacts on phagocytic cells according to their structure. Experimental and clinical studies have consistently shown that LE modify monocyte/macrophage and polymorphonuclear phagocytosis. The inhibitory effect of LE on the functional activity of the phagocytic system, although still clinically controversial, may have a harmful impact because total parenteral nutrition with lipids may be recommended in hypercatabolic conditions where inflammation and infection are present. LE based on triglycerides containing long chain fatty acids (termed long chain triglycerides or LCT) are the main parenteral fat source and are typically rich in n-6 polyunsaturated fatty acids. They may have adverse effects on the immune system, especially when given in high doses over a short period of time. However when administered properly they can be used safely. LE containing medium chain triglycerides (MCT) may have some advantages because of their positive effects on polymorphonuclear cells, macrophages, and cytokine production, particularly in critically ill or immunocompromised patients. New parenteral LE containing n-3 polyunsaturated fatty acids or monounsaturated olive oil are already available in Europe. Judicious use of these new LE is mandatory especially relating on their potential impact on the immune system. New experimental and clinical studies are required to further establish the role of LE in clinical nutrition.

Phagocytosis and killing of Candida albicans by human neutrophils after exposure to structurally different lipid emulsions

BACKGROUND

To test the hypothesis that structurally different lipid emulsions have distinct immune-modulating properties, we analyzed the elimination of Candida albicans by neutrophils after exposure to various emulsions.

METHODS

Neutrophils from 8 volunteers were incubated in physiologic 5 mmol/L emulsions containing long-chain- (LCT), medium-chain- (MCT), mixed LCT/MCT-, alpha-tocopherol-enriched LCT/MCT (LCT/MCT-E), or structured lipids (SL). After washing, the neutrophils were incubated with C. albicans. Phagocytosis was measured as the number of yeast-associated neutrophils relative to the total neutrophil count. Killing was expressed as the percentage of Candida survival relative to the initial yeast cell count.

RESULTS

No significant differences in yeast-neutrophil association could be demonstrated after neutrophil incubation in various lipid emulsions or medium, after correction for non-specific adhesion. However, although Candida survival after 1 hour incubation with non-lipid-exposed neutrophils amounted to 53% +/- 11% and was not influenced by LCT (60% +/- 11%), LCT/MCT (78% +/- 7%), LCT/MCT-E (72% +/- 12%), and SL (67% +/- 6%), pure MCT (70% +/- 13%) significantly impaired the killing capacity of neutrophils.

CONCLUSIONS

The decreased killing capacity of neutrophils after exposure to medium-chain fatty acid-containing emulsions and the absence of this effect with LCT suggest that lipid emulsions influence the elimination of C. albicans depending on the triglyceride chain length.

Effects of structurally different lipid emulsions on human neutrophil migration

AIM

To test the hypothesis that structurally different lipid emulsions have distinct immunomodulatory properties, we analysed neutrophil migration in the presence of various lipid emulsions.

METHOD

Neutrophils of 8 volunteers were pre-incubated in medium or physiological 2.5 mM emulsions containing long-chain (LCT), medium-chain (MCT), mixed LCT/MCT, alpha -tocopherol-enriched LCT/MCT (LCT/MCT-E) or structured triglycerides (SL). Thereafter, the cells were put on top of 3 microm-pore-sized cell culture filters and incubated for one hour in the presence or absence of a chemo-attractant. Neutrophil migration was measured as the percentage of cells that had passed the filter in the presence (chemotaxis) or absence (random migration) of a chemotactic factor.

RESULTS

Compared to lipid-free incubation (19+/-1%) random neutrophil migration significantly decreased with LCT/MCT (11+/-2%), LCT/MCT-E (12+/-2) and MCT (5+/-2%), while LCT (18+/-3%) and SL (20+/-1%) had no effect. N-formyl-methionyl-leucyl-phenylalanine- (fMLP, 10(-8)M) or zymosan-activated-serum-induced (ZAS, 10%) filter passage under lipid-free conditions amounted to 61+/-14% and 70+/-13%, respectively. These values decreased with LCT/MCT to 11+/-9% and 15+/-7%; with LCT/MCT-E to 18+/-10% and 28+/-12%; with SL to 39+/-18% and 57+/-14%, and with MCT to 5+/-2% and 10+/-6%, (all P<0.01), while LCT had no effect. Compared to LCT/MCT, the alpha -tocopherol-enriched formulation significantly increased ZAS- and fMLP-induced chemotaxis. fMLP-induced chemotaxis decreased in direct proportion to LCT/MCT triglyceride concentration.

CONCLUSIONS

Human neutrophil migration is distinctively inhibited by structurally different lipid emulsions, depending on triglyceride chain-length and concentration as well as alpha -tocopherol content.

Medium-chain, triglyceride-containing lipid emulsions increase human neutrophil beta2 integrin expression, adhesion, and degranulation

BACKGROUND

To test the hypothesis that lipid emulsions with different triglyceride structures have distinct immunomodulatory properties, we analyzed human neutrophil adhesion and degranulation after lipid incubation.

METHODS

Neutrophils, isolated from the blood of 10 healthy volunteers, were incubated in medium or physiologic (2.5 mmol/L) emulsions containing long-chain (LCT), medium-chain (MCT), mixed LCT/MCT, or structured (SL) triglycerides. Expression of adhesion molecules and degranulation markers was evaluated by flow cytometry. Also, functional adhesion was investigated by means of a flow cytometric assay using fluorescent beads coated with the integrin ligand intercellular adhesion molecule (ICAM)-1.

RESULTS

Although LCT and SL had no effect, LCT/MCT significantly increased expression of the beta2 integrins lymphocyte-function-associated antigen 1 (+18%), macrophage antigen 1 (+387%), p150,95 (+82%), and (alphaDbeta2 (+230%). Degranulation marker expression for azurophilic (CD63, +210%) and specific granules (CD66b, +370%) also significantly increased, whereas L-selectin (CD62L, -70%) decreased. The effects of LCT/MCT were mimicked by the MCT emulsion. ICAM-1 adhesion (% beads bound) was increased by LCT/MCT (34% +/- 4%), whereas LCT (19% +/-3%) and SL (20% +/- 2%) had no effect compared with medium (17% +/- 3%).

CONCLUSIONS

LCT/MCT and MCT, contrary to LCT and SL emulsions, increased neutrophil beta2 integrin expression, adhesion, and degranulation. Apart from other emulsion constituents, triglyceride chain length might therefore be a key feature in the interaction of lipid emulsions and the phagocyte immune system.

Influence of structurally different lipid emulsions on human neutrophil oxygen radical production

BACKGROUND

The aim of this study was to evaluate immunomodulatory properties of lipid emulsions applied in parenteral nutrition by measuring neutrophil oxygen radical production (the 'respiratory burst') after lipid incubation.

MATERIALS AND METHODS

Neutrophils, isolated from the blood of 10 healthy individuals, were incubated in medium or in lipid emulsions in a physiological concentration (2.5 mmol L-1) containing long-chain [Intralipid (LCT)], mixed medium and long-chain [Lipofundin (LCT/MCT)] or structured triglycerides (SL). After washing and stimulation with phorbol 12-myristate 13-acetate (PMA) or serum-treated zymosan (STZ) particles, the respiratory burst was evaluated by measuring maximum oxygen uptake, superoxide and hydrogen peroxide production rates and chemiluminescence.

RESULTS

Unlike LCT and SL, LCT/MCT increased PMA- and STZ-induced oxygen uptake rate by 45% and 31% respectively (both P = 0.006 compared with medium) as well as superoxide (+56%, P = 0.006) and hydrogen peroxide (+14%, P = 0.04) production, within 5 min after stimulation. Increased LCT/MCT-mediated early respiratory burst was confirmed by decreased PMA- (-65%) and STZ-stimulated (-54%) chemiluminescence peak time (time after stimulation to peak) in combination with unchanged peak height (maximum rate of radical production). Late respiratory burst (within 2 h) of LCT/MCT, indicated by overall luminescence (overall radical production), remained unchanged (PMA) or decreased (STZ, P = 0.02). The addition of 2.5 mmol L-1 LCT/MCT or MCT emulsion to unstimulated neutrophils, in contrast to LCT and SL, resulted in significant luminescence.

CONCLUSIONS

Early neutrophil respiratory burst is accelerated by the LCT/MCT emulsion Lipofundin, whereas LCT (Intralipid) and structured lipid emulsions exert no effect. MCT-containing emulsions, contrary to LCT and structured lipid emulsions, can induce oxygen radical production in unstimulated neutrophils.

Effect of parenteral medium- and long-chain triglycerides on lymphocytes subpopulations and functions in patients with acquired immunodeficiency syndrome: a prospective study

BACKGROUND

Total parenteral nutrition (TPN) may offer significant clinical benefit in malnourished patients with acquired immunodeficiency syndrome (AIDS). However, the immunologic effect of parenteral lipids remains unknown in these severely immunodepressed patients.

METHODS

We undertook a prospective randomized double-blind multicenter study comparing the effects of two i.v. lipid emulsions used during TPN: long-chain triglycerides (LCT) or balanced emulsion of long-and medium-chain triglycerides (LCT/MCT). Thirty-three AIDS patients requiring TPN for wasting and reduced oral intake were allocated randomly to receive a ternary TPN mixture consisting of 1.5 g/kg/d proteins, 18 kcal/kg/d lipids, and 12 Kcal/kg/d carbohydrates for 6 days. The following tests were performed at days 0 and 7: immunoglobulins, complement fractions, lymphocyte subpopulations count, and lymphocyte proliferation with mitogens.

RESULTS

Patients were all severely malnourished (weight loss: -14.0 +/- 1.3 kg). No clinical or biological differences were observed between the groups at baseline. At day 7, both groups reported a significant increase in weight. Patients in the LCT group exhibited a significant decrease in phytohemagglutinin A response (p = .04) compared with baseline. Patients in the LCT/MCT group exhibited a lower level of IgM (p = .03) and significant increase in C3 fraction (p = .03) compared with baseline. They also showed a tendency to have a higher CD4/CD8 lymphocyte ratio (p = .07), whereas other immunological parameters remained unchanged

CONCLUSIONS

Parenteral ternary mixture containing LCT or LCT/MCT are clinically well tolerated in AIDS patients over 6 days. With 2 g/kg/d of lipids, LCT seems to induce significant abnormalities in lymphocyte function. Such abnormalities are not observed with LCT/MCT.

Effect of total parenteral nutrition with different lipid emulsions of human monocyte and neutrophil functions

Parenteral nutrition (TPN) with lipid emulsions is claimed to be associated with impaired monocyte (M) and neutrophil (N) functions. Long-chain triglycerides (LCT) and a mixture containing 50% medium-chain triglycerides (MCT) and 50% LCT, currently used in nutritional therapy with TPN, were evaluated for their ex vivo effects on human N and M chemotaxis, phagocytosis, bacterial killing, and oxidative metabolism by nitroblue tetrazolium reduction test. Cell functions were examined in a randomized, crossover, blind trial in 10 malnourished patients with gastric cancer. Prior to the operation (2 wk), central TPN (40 kcal/kg) with 25% of caloric energy provided as LCT or MCT/LCT emulsion was infused over 48 h. After the crossover period fat-free TPN was given over 48 h. Function tests were done for N and M before and after each lipid emulsion infusion. Every cell function test performed for each patient was controlled by another test done in healthy adult volunteers and the results were compared with the normal range of values previously established for a healthy adult population. All the patients completed the studies without complications. Crossover validity was statistically established. Bacterial killing was the only function reduced in neutrophils after LCT emulsion (% killed bacteria = 79.0 +/- 8.5 versus 67.4 +/- 19.2; P < 0.05), although this function remained within the normal range values in 80% of the patients. In conclusion, the lipid emulsions did not affect any monocyte functions and only moderately decreased neutrophil bacterial killing.

Influence of medium-chain triglyceride-based lipid emulsion on rat polymorphonuclear cell functions

Intravenous lipid emulsions are used as energy and essential fatty acids sources. There are controversial reports postulating in vitro and in vivo inhibitory effects of long-chain triglycerides (LCT) upon the blood polymorphonuclear leukocytes (PMNL) functions. In the present study the in vivo and in vitro effects of LCT and a physical mixture of medium- and long-chain triglycerides (MCT/LCT) emulsions were investigated on select PMNL functions, i.e., chemotaxis, phagocytosis, and bacterial killing. Blood from 20 rats was incubated with LCT, MCT, MCT/LCT, and saline, respectively. MCT-containing emulsions exhibited an inhibitory effect on all PMNL functions investigated, whereas LCT exerted an effect on the phagocytic index only. The administration of a parenteral supply of LCT, MCT/LCT, and saline for 30 h followed by saline infusion for 14 h in discontinuous mode did not influence any of the investigated PMNL functions. Similarly, continuous infusion over 44 h at increasing infusion rates up to 1.5 mL/h did not affect the PMNL functions. The obvious difference between in vitro and in vivo response of the PMNL model emphasizes the necessity for continuous monitoring of in vivo conditions. Appropriate interpretation of the data requires continuous circumspection and consideration of trials in a clinical setting.