Parenteral medium-chain triglyceride-induced neutrophil activation is not mediated by a Pertussis Toxin sensitive receptor

The olive oil-based lipid clinoleic blocks leukocyte recruitment and improves survival during systemic inflammation: a comparative in vivo study of different parenteral lipid emulsions

Although fish oil-based and olive oil-based lipid emulsions have been shown to exert anti-inflammatory functions, the immunomodulating properties of lipids are still controversial. Therefore, we investigated the anti-inflammatory effect of three different parenterally administered lipid emulsions in vivo: olive oil-based Clinoleic, fish oil-based Smoflipid, and soybean oil-based Lipofundin. We observed leukocyte recruitment in inflamed murine cremaster muscle using intravital microscopy and survival in a murine model of LPS-induced systemic inflammation and analyzed expression of leukocyte and endothelial adhesion molecules. Olive oil-based Clinoleic and fish oil-based Smoflipid profoundly inhibited leukocyte adhesion compared to Lipofundin during LPS-induced inflammation of the murine cremaster muscle. In the trauma model of cremaster muscle inflammation, Lipofundin was the only lipid emulsion that even augmented leukocyte adhesion. In contrast to Smoflipid and Lipofundin, Clinoleic effectively blocked leukocyte recruitment and increased survival during lethal endotoxemia. Flow chamber experiments and analysis of adhesion molecule expression suggest that both endothelial and leukocyte driven mechanisms might contribute to anti-inflammatory effects of Clinoleic. We conclude that the anti-inflammatory properties of Clinoleic are superior to those of Smoflipid and Lipofundin even during systemic inflammation. Thus, these results should stimulate further studies investigating parenteral lipids as an anti-inflammatory strategy in critically ill patients.

Whole blood gene expression profile associated with spontaneous preterm birth in women with threatened preterm labor

Threatened preterm labor (TPTL) is defined as persistent premature uterine contractions between 20 and 37 weeks of gestation and is the most common condition that requires hospitalization during pregnancy. Most of these TPTL women continue their pregnancies to term while only an estimated 5% will deliver a premature baby within ten days. The aim of this work was to study differential whole blood gene expression associated with spontaneous preterm birth (sPTB) within 48 hours of hospital admission. Peripheral blood was collected at point of hospital admission from 154 women with TPTL before any medical treatment. Microarrays were utilized to investigate differential whole blood gene expression between TPTL women who did (n = 48) or did not have a sPTB (n = 106) within 48 hours of admission. Total leukocyte and neutrophil counts were significantly higher (35% and 41% respectively) in women who had sPTB than women who did not deliver within 48 hours (p<0.001). Fetal fibronectin (fFN) test was performed on 62 women. There was no difference in the urine, vaginal and placental microbiology and histopathology reports between the two groups of women. There were 469 significant differentially expressed genes (FDR<0.05); 28 differentially expressed genes were chosen for microarray validation using qRT-PCR and 20 out of 28 genes were successfully validated (p<0.05). An optimal random forest classifier model to predict sPTB was achieved using the top nine differentially expressed genes coupled with peripheral clinical blood data (sensitivity 70.8%, specificity 75.5%). These differentially expressed genes may further elucidate the underlying mechanisms of sPTB and pave the way for future systems biology studies to predict sPTB.

Oral supplementation of medium-chain fatty acids during the dry period supports the neutrophil viability of peripartum dairy cows

A randomised clinical trial was conducted to explore the effect of orally supplemented medium-chain fatty acids (MCFA) to heifers and cows starting 6-8 weeks prior to expected calving date on blood and milk polymorphonuclear neutrophilic leucocyte (PMNL) apoptosis between 1 and 3 d in milk (DIM). The effects of MCFA-supplementation on the likelihood of intramammary infections (IMI) in early lactation, and test-day somatic cell count (SCC) and average daily milk yield (MY) during the first 4 months of lactation were evaluated as well. Twenty-two animals were included of which half were orally supplemented with MCFA starting 6-8 weeks prior to calving and half served as non-supplemented controls. The PMNL viability in both blood and milk was quantified using dual-colour flow cytometry with fluorescein-labelled annexin and propidium iodide. In non-supplemented animals, % blood PMNL apoptosis significantly increased between start of supplementation and early lactation, reflecting a potential reduction in innate immune capacity, whereas this was not true in the MCFA-supplemented animals. Similar results were seen in milk PMNL apoptosis. Overall, the % apoptotic milk PMNL between 1 and 3 DIM was significantly lower in the MCFA-supplemented group compared with the non-supplemented group. There was no substantial effect of oral MCFA-supplementation on the likelihood of quarter IMI nor on the composite test-day milk SCC or average daily MY. In conclusion, oral MCFA-supplementation starting 6-8 weeks before expected calving date supported the blood and milk neutrophil viability in early lactating dairy cows. Still, this was not reflected in an improvement of udder health nor MY in early and later lactation. The results should trigger research to further unravel the mechanisms behind the observed immunomodulating effect, and the potential relevance for the cows' performances throughout lactation.

Short-term infusion of a fish oil-based lipid emulsion modulates fatty acid status, but not immune function or (anti)oxidant balance: a randomized cross-over study

BACKGROUND AND AIMS

Studies suggest clinical benefits of parenteral fish oil (FO), rich in n-3 polyunsaturated fatty acids (PUFAs), over soyabean oil (SO), rich in n-6 PUFAs, in patients with pro-inflammatory conditions such as sepsis and trauma. Because the mechanisms behind these observations remain unclear, the present study explored the effects of intravenous infusion of FO and SO on fatty acid incorporation, immune functions and (anti)oxidant balance in healthy human volunteers.

METHODS

Saline, a SO emulsion and a FO emulsion were administered for one hour on three consecutive days at a rate of 0·2 g/kg BW/h to eight subjects in a randomized cross-over design with a 3-week interval between treatments. Plasma phospholipid and peripheral blood mononuclear cell (PBMC) fatty acid compositions, and leucocyte counts and functions were assessed prior to the first infusion (T = 0, baseline) and 1 day (T = 4, early effects) and 8 days (T = 11, late effects) after the third infusion.

RESULTS

Fish oil infusion significantly increased n-3 PUFA proportions and decreased n-6 PUFA proportions in plasma phospholipids and PBMCs. There were no differences in immune functions or (anti)oxidant balance between treatments at any time.

CONCLUSIONS

The present lipid infusion protocol appears to be safe and well tolerated and provides significant incorporation of n-3 PUFAs into plasma phospholipids and PBMCs. In the absence of overt inflammation, no direct effects of FO were observed on immune function or (anti)oxidant balance. This model may be useful to evaluate effects of parenteral lipids in other settings, for example in individuals displaying an inflammatory state.

Parenteral lipids impair pneumococcal elimination by human neutrophils

BACKGROUND

Lipid-induced modulation of phagocyte function seems to contribute to increased susceptibility to infections in patients on parenteral nutrition, and an increased risk for development of pneumonia has been observed in this group. The role of various structurally different lipid emulsions, however, remains unclear. In this study, we therefore assessed phagocyte function, as the capacity of neutrophils to eliminate Streptococcus pneumoniae (i.e. combined result of phagocytosis and killing), in the presence of these lipids.

MATERIALS AND METHODS

Neutrophils from six healthy volunteers were incubated for 1 h in emulsions (5 mmol L(-1)) derived from soybean- (LCT), fish- (VLCT), olive- (LCT-MUFA), mixed soybean/coconut oils (LCT/MCTs) or structured lipids (SL). After opsonization of the pneumococci (strain OREP-4) by human immunoglobulins, bacteria and neutrophils were incubated in the presence of complement. Next, pneumococcal elimination was evaluated and expressed as the percentage of bacteria eliminated relative to the initial bacterial numbers in neutrophil-free samples.

RESULTS

Neutrophils that were not exposed to lipids showed a pneumococcal elimination capacity of 75 +/- 3% (mean +/- SD). This significantly decreased after exposure to LCT-MUFA (70 +/- 6%), VLCT (67 +/- 2%), SL (63 +/- 9%), LCT (66 +/- 10%) and LCT/MCT (47 +/- 15%).

CONCLUSION

These data demonstrate that parenteral lipids impair the microbial elimination capacity of neutrophils in a structure-dependent manner. In accordance with our previously reported in vitro effect on a range of phagocyte functions, LCT/MCT is by far the most potent in this respect.

Free fatty acid receptors: emerging targets for treatment of diabetes and its complications

Fatty acids (FAs) are important as metabolic substrates and as structural components of biological membranes. However, they also function as signalling molecules. Recently, a series of G protein-coupled receptors (GPRs) for FAs has been described and characterized. These receptors have differing specificities for FAs of differing chain length and degree of saturation, for FA derivatives such as oleoylethanolamide, and for oxidized FAs. They are a critical component of the body's nutrient sensing apparatus, and small molecule agonists and antagonists of these receptors show considerable promise in the management of diabetes and its complications. Agonists of the long-chain free fatty acid receptors FFAR1 and GPR119 act as insulin secretagogues, both directly and by increasing incretins. Although, drugs acting at short-chain FFA receptors (FFAR2 and FFAR3) have not yet been developed, they are attractive targets as they regulate nutrient balance through effects in the intestine and adipose tissue. These include regulation of the secretion of cholecystokinin, peptide YY and leptin. Finally, GPR132 is a receptor for oxidized FAs, which may be a sensor of lipid overload and oxidative stress, and which is involved in atherosclerosis. Regulation of its signalling pathways with drugs may decrease the macrovascular risk experienced by diabetic patients. In summary, FA receptors are emerging drug targets that are involved in the regulation of nutrient status and carbohydrate tolerance, and modulators of these receptors may well figure prominently in the next generation of antidiabetic drugs.