Rosaleen Devery

Conjugated linoleic acid biosynthesis by human‐derived Bifidobacterium species

Aims: To assess strains of Lactobacillus, Lactococcus, Pediococcus and Bifidobacterium for their ability to produce the health‐promoting fatty acid conjugated linoleic acid (CLA) from free linoleic acid.

Influence of breed on bovine milk cis-9, trans-11-conjugated linoleic acid content

The influence of animal breed on the profile of fatty acids in milk and particularly on the concentration of cis-9, trans-11 octadecadienoic acid, a conjugated lineoleic acid (CLA) was investigated using four breeds of cows, Irish Holstein/Friesian (IH, n=23), Dutch Holstein/Friesian (DH, n=22), Montbeliardes (MB, n=29) and Normandes (NM, n=27), on pasture. All cows were grazed together in one group. Milk fat CLA concentration from MB were significantly higher (P<0.05) than from DH at one of the two sampling times, while the CLA content of milk fat from NM, IH and DH was not significantly different at either sampling time. Milk fat CLA concentrations between the four breeds ranged from 14.7 to 18.6 mg/g fat, while the variation in milk fat CLA between individual cows within the four breeds ranged from 4.8 to 35.6 mg/g fat. There were significant correlations between milk fat CLA concentrations of individual cows within NM (P<0.001), MB (P<0.001) and IH (P<0.001) and the correlation was close to being significant for DH cows (P=0.076) at two sampling dates. In terms of total fatty acid profiles, DH had higher (P<0.05) C16:0 concentrations than the other breeds. The IH had a higher (P<0.05) C16:0 than the MB. The C18:0 content was higher (P<0.05 at least) in milk fat from NM and MB than from DH and total C18:1 concentrations were close to being significantly higher (P=0.067) in the MB than in the IH. The data indicate that animal breed has some influence over the CLA content of milk and that cows yielding high levels of milk fat CLA sustain this production over time. While there were some significant differences between the breeds in the concentrations of C16:0, C18:0 and C18:1 it is unlikely that they are large enough to be of practical importance.

The Health Promoting Properties of the Conjugated Isomers of α-Linolenic Acid

The bioactive properties of the conjugated linoleic acid (CLA) isomers have long been recognised and are the subject of a number of excellent reviews. However, despite this prominence the CLA isomers are not the only group of naturally occurring dietary conjugated fatty acids which have shown potent bioactivity. In a large number of in vitro and in vivo studies, conjugated α-linolenic acid (CLNA) isomers have displayed potent anti-inflammatory, immunomodulatory, anti-obese and anti-carcinogenic activity, along with the ability to improve biomarkers of cardio-vascular health. CLNA isomers are naturally present in high concentrations in a large variety of seed oils but can also be produced in vitro by strains of lactobacilli and bifidobactena through the activity of the enzyme linoleic acid isomerase on α-linolenic acid. In this review, we will address the possible therapeutic roles that CLNA may play in a number of conditions afflicting Western society and the mechanisms through which this activity is mediated.

Intestinal Bifidobacteria That Produce trans-9, trans-11 Conjugated Linoleic Acid: A Fatty Acid With Antiproliferative Activity Against Human Colon SW480 and HT-29 Cancer Cells

Abstract: Bifidobacterium breve species of human intestinal origin have the ability to synthesize cis-9, trans-11 (c9, t11) conjugated linoleic acid (CLA) from free linoleic acid. In this study, the ability of Bifidobacterium species to isomerize C18 polyunsaturated fatty acids was investigated, and the antiproliferative activities of the two main microbially produced CLA isomers were assessed. Linoleic acid was converted principally to c9, t11 CLA and lesser amounts of t9, t11 CLA, whereas c9, t11 CLA was converted mainly to t9, t11 CLA. Likewise, t10, c12 CLA was converted principally to t9, t11 CLA, which was incorporated into the bacterial cell membranes. To examine the antiproliferative effect of the two main CLA isomers formed, SW480 and HT-29 human colon cancer cells were cultured in the presence of c9, t11 CLA and t9, t11 CLA. The t9, t11 CLA had a more potent antiproliferative effect than c9, t11 CLA. It is tempting to suggest that the ability of Bifidobacterium to produce such bioactive metabolites may be associated with the beneficial effects of bifidobacteria present in the human gastrointestinal tract.

Mining the microbiota of the neonatal gastrointestinal tract for conjugated linoleic acid-producing bifidobacteria.

ABSTRACT This study was designed to isolate different strains of the genus Bifidobacterium from the fecal material of neonates and to assess their ability to produce the cis-9, trans-11 conjugated linoleic acid (CLA) isomer from free linoleic acid. Fecal material was collected from 24 neonates aged between 3 days and 2 months in a neonatal unit (Erinville Hospital, Cork, Ireland). A total of 46 isolates from six neonates were confirmed to be Bifidobacterium species based on a combination of the fructose-6-phosphate phosphoketolase assay, RAPD [random(ly) amplified polymorphic DNA] PCR, pulsed-field gel electrophoresis (PFGE), and partial 16S ribosomal DNA sequencing. Interestingly, only 1 of the 11 neonates that had received antibiotic treatment produced bifidobacteria. PFGE after genomic digestion with the restriction enzyme XbaI demonstrated that the bifidobacteria population displayed considerable genomic diversity among the neonates, with each containing between one and five dominant strains, whereas 11 different macro restriction patterns were obtained. In only one case did a single strain appear in two neonates. All genetically distinct strains were then screened for CLA production after 72 h of incubation with 0.5 mg of free linoleic acid ml−1 by using gas-liquid chromatography. The most efficient producers belonged to the species Bifidobacterium breve, of which two different strains converted 29 and 27% of the free linoleic acid to the cis-9, trans-11 isomer per microgram of dry cells, respectively. In addition, a strain of Bifidobacterium bifidum showed a conversion rate of 18%/μg dry cells. The ability of some Bifidobacterium strains to produce CLA could be another human health-promoting property linked to members of the genus, given that this metabolite has demonstrated anticarcinogenic activity in vitro and in vivo.

Conjugated linoleic acid in bovine milk fat : a food-based approach to cancer chemoprevention

Abstract Conjugated linoleic acid (CLA) is a naturally occurring fatty acid found in animal and dairy fats that exhibits a number of health benefits. An explosion of research has demonstrated the importance of CLA in health-promotion, e.g. as a dietary chemopreventive agent in addition to exhibiting anticatabolic and antiatherosclerotic properties. This has led to efforts to manipulate naturally the CLA content of milk and animal tissue by dietary intervention. Such research may lead to the development of new high CLA-containing ‘functional foods’ designed for cancer chemoprevention.

Modulation of arachidonic acid distribution by conjugated linoleic acid isomers and linoleic acid in MCF-7 and SW480 cancer cells

The relationship between growth and alterations in arachidonic acid (AA) metabolism in human breast (MCF-7) and colon (SW480) cancer cells was studied. Four different fatty acid preparations were evaluated: a mixture of conjugated linoleic acid (CLA) isomers (c9,t11, t10,c12,c11,t13, and minor amounts of other isomers), the pure c9,t11-CLA isomer, the pure t10,c12-CLA isomer, and linoleic acid (LA) (all at a lipid concentration of 16 μg/mL). 14C-AA uptake into the monoglyceride fraction of MCF-7 cells was significantly increased following 24 h incubation with the CLA mixture (P<0.05) and c9,t11-CLA (P<0.02). In contrast to the MCF-7 cells, 14C-AA uptake into the triglyceride fraction of the SW480 cells was increased while uptake into the phospholipids was reduced following treatment with the CLA mixture (P<0.02) and c9,t11-CLA (P<0.05). Distribution of 14C-AA among phospholipid classes was altered by CLA treatments in both cell lines. The c9,t11-CLA isomer decreased (P<0.05) uptake of 14C-AA into phosphatidylcholine while increasing (P<0.05) uptake into phosphatidylethanolamine in both cell lines. Both the CLA mixture and the t10,c12-CLA isomer increased (P<0.01) uptake of 14C-AA into phosphatidylserine in the SW480 cells but had no effect on this phospholipid in the MCF-7 cells. Release of 14C-AA derivatives was not altered by CLA treatments but was increased (P<0.05) by LA in the SW480 cell line. The CLA mixture of isomers and c9,t11-CLA isomer inhibited 14C-AA conversion to 14C-prostaglandin E2 (PGE2) by 20–30% (P<0.05) while increasing 14C-PGF2α by 17–44% relative to controls in both cell lines. LA significantly (P<0.05) increased 14C-PGD2 by 13–19% in both cell lines and increased 14C-PGE2 by 20% in the SW480 cell line only. LA significantly (P<0.05) increased 5-hydroperoxyeicosatetraenoate by 27% in the MCF-7 cell line. Lipid peroxidation, as determined by increased levels of 8-epi-prostaglandin F2α (8-epi-PGF2α), was observed following treatment with c9,t11-CLA isomer in both cell lines (P<0.02) and with t10,c12-CLA isomer in the MCF-7 cell line only (P<0.05). These data indicate that the growth-promoting effects of LA in the SW480 cell line may be associated with enhanced conversion of AA to PGE2 but that the growth-suppressing effects of CLA isomers in both cell lines may be due to changes in AA distribution among cellular lipids and an altered prostaglandin profile.

Vaccenic acid (t11-18:1) is converted to c9,t11-CLA in MCF-7 and SW480 cancer cells.

The aims of this study were to determine whether vaccenic acid (VA; t11–18∶1) is converted to c9,t11-CLA in human mammary (MCF-7) and colon (SW480) cancer cell lines and whether VA influences cell viability and other CLA-bioresponsive markers. When cells were incubated in the presence of VA at concentrations of 5 to 20 μg/mL, both VA and c9,t11-CLA increased in cellular lipids in a dose-dependent manner. After 4 d of incubation of SW480 and MCF-7 cells with VA (20 μg/mL), c9,t11-CLA increased from undetectable levels to 8.57 and 12.14 g/100 g FAME in cellular lipids, respectively. VA supplementation for 4 d at 5, 10, and 15 μg/mL had no effect on cell growth, whereas 20 μg/mL significantly (P<0.05) reduced cell growth in both cell lines. VA (20 μg/mL) treatment induced DNA fragmentation and significantly (P<0.05) depeleted cytosolic GSH levels in the SW480 cell line after 4 d of incubation, suggesting that apoptosis was the mode of cell death induced by VA. Both VA and c9,t11-CLA reduced (P<0.05) total ras expression in SW480 cells. 14C-Arachidonic acid uptake into the MG fraction was significantly increased (P<0.05) in both cell lines while uptake into the phospholipid fraction decreased in response to VA. VA treatment significantly (P<0.05) increased 8-epi-prostaglandin F2α in both cell lines. The data indicate that growth suppression and cellular responses of both cells lines are likely mediated by VA desaturation to c9,t11-CLA via Δ9-desaturase.

The Role of Short-Chain Fatty Acids, Produced by Anaerobic Bacteria, in the Cystic Fibrosis Airway

RATIONALE Anaerobic bacteria are present in large numbers in the airways of people with cystic fibrosis (PWCF). In the gut, anaerobes produce short-chain fatty acids (SCFAs) that modulate immune and inflammatory processes. OBJECTIVES To investigate the capacity of anaerobes to contribute to cystic fibrosis (CF) airway pathogenesis via SCFAs. METHODS Samples of 109 PWCF were processed using anaerobic microbiological culture with bacteria present identified by 16S RNA sequencing. SCFA levels in anaerobic supernatants and bronchoalveolar lavage (BAL) were determined by gas chromatography. The mRNA and/or protein expression of two SCFA receptors, GPR41 and GPR43, in CF and non-CF bronchial brushings and 16HBE14o(-) and CFBE41o(-) cells were evaluated using reverse transcription polymerase chain reaction, Western blot analysis, laser scanning cytometry, and confocal microscopy. SCFA-induced IL-8 secretion was monitored by ELISA. MEASUREMENTS AND MAIN RESULTS Fifty-seven (52.3%) of 109 PWCF were anaerobe positive. Prevalence increased with age, from 33.3% to 57.7% in PWCF younger (n = 24) and older (n = 85) than 6 years of age. All evaluated anaerobes produced millimolar concentrations of SCFAs, including acetic, propionic, and butyric acids. SCFA levels were higher in BAL samples of adults than in those of children. GPR41 levels were elevated in CFBE41o(-) versus 16HBE14o(-) cells; CF versus non-CF bronchial brushings; and 16HBE14o(-) cells after treatment with cystic fibrosis transmembrane conductance regulator inhibitor CFTR(inh)-172, CF BAL, or inducers of endoplasmic reticulum stress. SCFAs induced a dose-dependent and pertussis toxin-sensitive IL-8 response in bronchial epithelial cells, with a higher production of IL-8 in CFBE41o(-) than in 16HBE14o(-) cells. CONCLUSIONS This study illustrates that SCFAs contribute to excessive production of IL-8 in CF airways colonized with anaerobes via up-regulated GPR41.

Validation of chromatographic analysis of cholesterol oxides in dried foods

Abstract Chromatographic techniques, such as high-performance liquid chromatography and gas chromatography, are now widely used as analytical tools for the detection of cholesterol oxidation products at low levels (parts per million) in food. Once a chromatographic method has been developed, it must be validated to establish its limitations in daily use. Validation with the requirements for testing a product while observing a defined procedure. It comprises sample preparation, analysis and evaluation of the results. This review addresses the criteria necessary for full validation of chromatographic methods used in cholesterol oxide analysis.