Dietaryn-3 andn-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids

Alterations of the fatty acid composition and lipid metabolome of breast muscle in chickens exposed to dietary mixed edible oils

The fatty acid composition of chicken's meat is largely influenced by dietary lipids, which are often used as supplements to increase dietary caloric density. The underlying key metabolites and pathways influenced by dietary oils remain poorly known in chickens. The objective of this study was to explore the underlying metabolic mechanisms of how diets supplemented with mixed or a single oil with distinct fatty acid composition influence the fatty acid profile in breast muscle of Qingyuan chickens. Birds were fed a corn-soybean meal diet supplemented with either soybean oil (control, CON) or equal amounts of mixed edible oils (MEO; soybean oil : lard : fish oil : coconut oil = 1 : 1 : 0.5 : 0.5) from 1 to 120 days of age. Growth performance and fatty acid composition of muscle lipids were analysed. LC-MS was applied to investigate the effects of CON v. MEO diets on lipid-related metabolites in the muscle of chickens at day 120. Compared with the CON diet, chickens fed the MEO diet had a lower feed conversion ratio (P < 0.05), higher proportions of lauric acid (C12:0), myristic acid (C14:0), palmitoleic acid (C16:1n-7), oleic acid (C18:1n-9), EPA (C20:5n-3) and DHA (C22:6n-3), and a lower linoleic acid (C18:2n-6) content in breast muscle (P < 0.05). Muscle metabolome profiling showed that the most differentially abundant metabolites are phospholipids, including phosphatidylcholines (PC) and phosphatidylethanolamines (PE), which enriched the glycerophospholipid metabolism (P < 0.05). These key differentially abundant metabolites - PC (14:0/20:4), PC (18:1/14:1), PC (18:0/14:1), PC (18:0/18:4), PC (20:0/18:4), PE (22:0/P-16:0), PE (24:0/20:5), PE (22:2/P-18:1), PE (24:0/18:4) - were closely associated with the contents of C12:0, C14:0, DHA and C18:2n-6 in muscle lipids (P < 0.05). The content of glutathione metabolite was higher with MEO than CON diet (P < 0.05). Based on these results, it can be concluded that the diet supplemented with MEO reduced the feed conversion ratio, enriched the content of n-3 fatty acids and modified the related metabolites (including PC, PE and glutathione) in breast muscle of chickens.

Effect of dietary fat type on intestinal digestibility of fatty acids, fatty acid profiles of breast meat and abdominal fat, and mRNA expression of lipid-related genes in broiler chickens

A group of 240-day-old Ross cockerels were used in a 4-week experiment to assess the effect of the fat type on the intestinal digestibility of fatty acids (FAs), the FA profiles of breast meat and abdominal fat, and the mRNA expression of six hepatic lipid-related genes. Experimental diets were supplemented with rapeseed oil, pork lard or palm oil at 60 g/kg. In the control diet, wheat starch was substituted for the fat source. The highest ileal digestibility of the fat and all FAs (except stearic acid) was observed in chickens fed lard. The content of fat in the breast meat of chickens was not significantly influenced by the fat supplements. The FA profiles of breast meat and abdominal fat reflected the FA composition of the diet. In the meat of chickens fed rapeseed oil, oleic acid was the predominant FA. Palmitic acid was the most abundant FA in the meat of chickens fed lard or palm oil. Oleic acid was the most abundant FA in the abdominal fat of all chickens. The highest mRNA expression of desaturases (Δ5-, Δ6- and Δ9-) was observed in chickens fed palm oil. The mRNA expression of hepatic FA synthase was higher in chickens fed palm oil or lard than in chickens fed rapeseed oil. The expression of HMG-CoA reductase was higher in chickens fed palm oil than in those fed rapeseed oil or lard. It can be concluded that rapeseed oil and lard are better sources of lipids than palm oil. These former two sources contain more digestible fatty acids and provide a lower concentration of SFAs in the meat and fat of chickens.

Conversion efficiency of α-linolenic acid to omega-3 highly unsaturated fatty acids in aerial insectivore chicks

Food availability and quality are both critical for growing young animals. In nature, swallows (Tachycineta bicolor) and other aerial insectivores feed on both aquatic insects, which are rich in omega-3 highly unsaturated fatty acids (HUFAs), and terrestrial insects, which contain considerably lower amounts of omega-3 HUFAs. Carnivorous mammals and fishes must obtain omega-3 HUFAs from their diet, as they have lost the capacity to convert the precursor omega-3 α-linolenic acid (ALA) into omega-3 HUFAs. Thus, the relative value of aquatic versus terrestrial insects depends not only on the fatty acid composition of the prey but also on the capacity of consumers to convert ALA into omega-3 HUFAs. We used a combination of stable-isotope-labeled fatty acid tracers to ask whether, and how efficiently, tree swallows can deposit newly synthesized omega-3 HUFAs into tissue. Our data show for the first time that tree swallows can convert ALA into omega-3 HUFAs deposited in liver and skeletal muscle. However, high tree swallow demand for omega-3 HUFAs combined with low ALA availability in natural terrestrial foods may strain their modest conversion ability. This suggests that while tree swallows can synthesize omega-3 HUFAs de novo, omega-3 HUFAs are ecologically essential nutrients in natural systems. Our findings thus provide mechanistic support for our previous findings and the importance of omega-3 HUFA-rich aquatic insects for tree swallows and most likely other aerial insectivores with similar niches.

Genetic parameters for fatty acids in intramuscular fat from feedlot-finished Nelore carcasses

The aim of the present study was to estimate covariance components and genetic parameters for beef fatty acid (FA) composition of intramuscular fat in the longissimus thoracis muscle in Nelore bulls finished in feedlot. Twenty-two FAs were selected. The heritability estimates for individual FAs ranged from 0.01 to 0.35. The heritability estimates for myristic (0.25 ± 0.09), palmitic (0.18 ± 0.07), oleic (0.28 ± 0.09), linoleic (0.16 ± 0.06) and α-linolenic (0.35 ± 0.10) FAs were moderate. Stearic, elaidic, palmitoleic, vaccenic, conjugated linoleic acid, docosahexanoic, eicosatrienoic and arachidonic FAs had heritability estimates below 0.15. The genetic-correlation estimates between the individual saturated FAs (SFAs) were low and negative between myristic and stearic FAs (–0.22 ± 0.84), moderate between palmitic and myristic FAs (0.58 ± 0.56) and negative between palmitic and stearic FAs (–0.69 ± 0.45). The genetic correlations between the individual long-chain polyunsaturated FAs (PUFAs) were positive and moderate (>0.30). However, the genetic-correlation estimates between long-chain PUFAs and α-linolenic acid were low (<0.30), except for the correlation between arachidonic and α-linolenic acids. The genetic correlation estimates of the sums of SFAs with monounsaturated fatty acids and omega 6 FAs were low (0.25 ± 0.59 and –0.02 ± 0.51 respectively), high with PUFAs and omega 9 FAs (–0.85 ± 0.15 and 0.86 ± 0.17 respectively) and moderate with omega 3FAs (–0.67 ± 0.26). The present study demonstrated the existence of genetic variation and, hence, the possibility to increase the proportion of healthy and favourable beef FAs through selection. The results obtained in the study have provided knowledge to elucidate the additive genetic influence on FA composition of intramuscular fat. In addition, genetic-relationship estimates of intramuscular FA profile help seek strategies for genetic selection or genetic-based diet management to enhance the FA profile in Zebu cattle.

Omega-3 long-chain polyunsaturated fatty acids support aerial insectivore performance more than food quantity

Once-abundant aerial insectivores, such as the Tree Swallow (Tachycineta bicolor), have declined steadily in the past several decades, making it imperative to understand all aspects of their ecology. Aerial insectivores forage on a mixture of aquatic and terrestrial insects that differ in fatty acid composition, specifically long-chain omega-3 polyunsaturated fatty acid (LCPUFA) content. Aquatic insects contain high levels of both LCPUFA and their precursor omega-3 PUFA, alpha-linolenic acid (ALA), whereas terrestrial insects contain much lower levels of both. We manipulated both the quantity and quality of food for Tree Swallow chicks in a full factorial design. Diets were either high-LCPUFA or low in LCPUFA but high in ALA, allowing us to separate the effects of direct LCPUFA in diet from the ability of Tree Swallows to convert their precursor, ALA, into LCPUFA. We found that fatty acid composition was more important for Tree Swallow chick performance than food quantity. On high-LCPUFA diets, chicks grew faster, were in better condition, and had greater immunocompetence and lower basal metabolic rates compared with chicks on both low LCPUFA diets. Increasing the quantity of high-LCPUFA diets resulted in improvements to all metrics of performance while increasing the quantity of low-LCPUFA diets only resulted in greater immunocompetence and lower metabolic rates. Chicks preferentially retained LCPUFA in brain and muscle when both food quantity and LCPUFA were limited. Our work suggests that fatty acid composition is an important dimension of aerial insectivore nutritional ecology and reinforces the importance of high-quality aquatic habitat for these declining birds.

Genetic correlation estimates between beef fatty acid profile with meat and carcass traits in Nellore cattle finished in feedlot

The objective of this study was to estimate the genetic-quantitative relationships between the beef fatty acid profile with the carcass and meat traits of Nellore cattle. A total of 1826 bulls finished in feedlot conditions and slaughtered at 24 months of age on average were used. The following carcass and meat traits were analysed: subcutaneous fat thickness (BF), shear force (SF) and total intramuscular fat (IMF). The fatty acid (FA) profile of the Longissimus thoracis samples was determined. Twenty-five FAs (18 individuals and seven groups of FAs) were selected due to their importance for human health. The animals were genotyped with the BovineHD BeadChip and, after quality control for single nucleotide polymorphisms (SNPs), only 470,007 SNPs from 1556 samples remained. The model included the random genetic additive direct effect, the fixed effect of the contemporary group and the animal's slaughter age as a covariable. The (co)variances and genetic parameters were estimated using the REML method, considering an animal model (single-step GBLUP). A total of 25 multi-trait analyses, with four traits, were performed considering SF, BF and IMF plus each individual FA. The heritability estimates for individual saturated fatty acids (SFA) varied from 0.06 to 0.65, for monounsaturated fatty acids (MUFA) it varied from 0.02 to 0.14 and for polyunsaturated fatty acids (PUFA) it ranged from 0.05 to 0.68. The heritability estimates for Omega 3, Omega 6, SFA, MUFA and PUFA sum were low to moderate, varying from 0.09 to 0.20. The carcass and meat traits, SF (0.06) and IMF (0.07), had low heritability estimates, while BF (0.17) was moderate. The genetic correlation estimates between SFA sum, MUFA sum and PUFA sum with BF were 0.04, 0.64 and -0.41, respectively. The genetic correlation estimates between SFA sum, MUFA sum and PUFA sum with SF were 0.29, -0.06 and -0.04, respectively. The genetic correlation estimates between SFA sum, MUFA sum and PUFA sum with IMF were 0.24, 0.90 and -0.67, respectively. The selection to improve meat tenderness in Nellore cattle should not change the fatty acid composition in beef, so it is possible to improve this attribute without affecting the nutritional beef quality in zebu breeds. However, selection for increased deposition of subcutaneous fat thickness and especially the percentage of intramuscular fat should lead to changes in the fat composition, highlighting a genetic antagonism between meat nutritional value and acceptability by the consumer.

Dietaryn-3 andn-6 Fatty Acids Alter Avian Pituitary Sensitivity

The effects of dietary saturated and polyunsaturated fatty acids (PUFAs) of the n-3 and n-6 series on avian pituitary sensitivity were investigated by infusing human growth hormone (GH) releasing hormone--fragment 1-29--and chicken luteinising hormone releasing hormone (LHRH) into catheterized broiler chickens. At 3 weeks of age three groups (n = 18; six birds per group) were fed for 6 weeks isonitrogenous and isoenergetic experimental diets containing 80 g/kg of edible tallow (saturated fatty acids), fish oil (n-3 PUFAs) or sunflower oil (n-6 PUFAs). Jugular catheterisation was performed under general anaesthesia during week four of the dietary treatments and the birds allowed 7 days post surgery to recover. A bolus of LHRH (20 microg/bird) and a GH releasing hormone (12.5 microg/kg) infusion was given on different days to each chicken and serial blood samples taken over a 1 h period. Plasma luteinising hormone and GH concentrations were measured by radioimmunoassay. Pre-infusion GH concentrations were similar for the tallow, fish and sunflower oil dietary groups (5.2 +/- 3.9, 5.2 +/- 1.0 and 6.1 +/- 3.1 ng/ml, respectively), however, GH concentration in response to the GH releasing hormone infusion was elevated in the sunflower oil group (44.7 +/- 5.7 ng/ml) when compared to chicken fed tallow (33.7 +/- 9.7ng/ml) or fish oil (21.3 +/- 5.0 ng/ml). There was a significant decrease (P < 0.05) in the clearance rate of plasma GH for the birds fed the fish oil compared with those fed sunflower oil with an intermediate value being observed in the tallow fed group. Pre-infusion plasma luteinising hormone concentrations for the birds fed tallow (3.2 +/- 0.7 ng/ml) were significantly elevated (P < 0.05) when compared to birds fed either the sunflower oil (0.84 +/- 0.25 ng.ml) or fish oil (0.93 +/- 0.22 ng/ml) diets. There were no significant differences between the dietary groups in either the maximal plasma luteinising concentration or its disappearance rate following the LHRH infusion. The data demonstrate that dietary fatty acids alter avian pituitary sensitivity and this modulation is determined by the nature of the dietary fat rather than the degree of saturation per se. In addition, this study also shows that dietary fats have a differential effect on pituitary cell activity and are specific to certain pituitary cell types.

Transcriptomic and metabolomic profiling of chicken adipose tissue in response to insulin neutralization and fasting

BACKGROUND

Domestic broiler chickens rapidly accumulate adipose tissue due to intensive genetic selection for rapid growth and are naturally hyperglycemic and insulin resistant, making them an attractive addition to the suite of rodent models used for studies of obesity and type 2 diabetes in humans. Furthermore, chicken adipose tissue is considered as poorly sensitive to insulin and lipolysis is under glucagon control. Excessive fat accumulation is also an economic and environmental concern for the broiler industry due to the loss of feed efficiency and excessive nitrogen wasting, as well as a negative trait for consumers who are increasingly conscious of dietary fat intake. Understanding the control of avian adipose tissue metabolism would both enhance the utility of chicken as a model organism for human obesity and insulin resistance and highlight new approaches to reduce fat deposition in commercial chickens.

RESULTS

We combined transcriptomics and metabolomics to characterize the response of chicken adipose tissue to two energy manipulations, fasting and insulin deprivation in the fed state. Sixteen to 17 day-old commercial broiler chickens (ISA915) were fed ad libitum, fasted for five hours, or fed but deprived of insulin by injections of anti-insulin serum. Pair-wise contrasts of expression data identified a total of 2016 genes that were differentially expressed after correction for multiple testing, with the vast majority of differences due to fasting (1780 genes). Gene Ontology and KEGG pathway analyses indicated that a short term fast impacted expression of genes in a broad selection of pathways related to metabolism, signaling and adipogenesis. The effects of insulin neutralization largely overlapped with the response to fasting, but with more modest effects on adipose tissue metabolism. Tissue metabolomics indicated unique effects of insulin on amino acid metabolism.

CONCLUSIONS

Collectively, these data provide a foundation for further study into the molecular basis for adipose expansion in commercial poultry and identify potential pathways through which fat accretion may be attenuated in the future through genetic selection or management practices. They also highlight chicken as a useful model organism in which to study the dynamic relationship between food intake, metabolism, and adipose tissue biology.

Dietary n-3 and n-6 fatty acids alter avian glucose metabolism

(1) This investigation studied the effects of dietary saturated and polyunsaturated fatty acids (PUFAs) from the n-3 and n-6 series on insulin action and glucose uptake in broiler chickens. (2) One-day-old male chicks were fed on a commercial starter diet for 3 weeks, randomly divided into three groups (n = 6) and fed ad libitum on isonitrogenous experimental diets of equal energy density for a further 6 weeks. The diets contained 20.8 g/100 g protein and 80 g/kg of either edible tallow, fish oil or sunflower oil, giving diets high in saturated fatty acids, n-S PUFAs or n-6 PUFAs, respectively. (3) Jugular catheterisation was performed under general anaesthesia during week 4 of the dietary treatments and the birds given 7 d post-surgery to recover. To estimate insulin action, a bolus glucose infusion (1 g/kg) was given to each chicken and sequential blood samples taken over a one-hour period. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose (2DG-3H glucose) was infused into each chicken (50 microCi) 2 d later. (4) Although there were no significant differences in glucose clearance rate following the glucose infusion, the maximal insulin release in response to the glucose infusion was higher in the tallow group than in either the n-3 or n-6 PUFA dietary groups. There were no significant differences in the clearance rate of 2DG-3H glucose. Labelled glucose incorporation into the breast muscle was greater in birds given fish oil than in birds given tallow and significantly greater than in birds given sunflower oil. (5) The data suggest that the type of dietary fat can influence glucose metabolism and that this change in glucose utilisation may alter the energy metabolism of the broiler.

Sunflower oil supplementation alters meat quality but not performance of growing partridges (Alectoris chukar)

This study was conducted to evaluate the effects of sunflower oil supplementation (0%, 3%, 6% and 9%) to partridge chicks (Alectoris chukar) on growth performance, nutrient digestibility and carcass characteristics. Feed consumption and live weight gain were responsive to dietary sunflower oil inclusion during the starter period, but not during the grower period. Increasing sunflower oil level linearly increased crude protein and fat digestibilities. Except for abdominal fat, weights of inedible parts and edible organs remained unchanged by the diets. The treatments linearly decreased weight and efficiency of carcass and weights of wings and breast and did not alter weights of thighs and neck. Breast meat saturated fatty acids decreased linearly by 17.9% and unsaturated fatty acids increased linearly by 10.6%, as sunflower oil level increased in the diets. Monounsaturated fatty acids decreased linearly by 27.3%, whereas polyunsaturated fatty acids increased linearly by 51%. Overall, n-3 (0.78% vs. 0.59%) and n-6 (42.6% vs. 29.8%) were greater in breast meat in treatment groups than in control group. In conclusion, sunflower addition into diets has minimal effects on performance of growing partridges, but significantly alters meat fatty acid composition.

Feeding flaxseed oil but not secoisolariciresinol diglucoside results in higher bone mass in healthy rats and rats with kidney disease

Flaxseed's oil and lignan, secoisolariciresinol diglucoside (SDG), are implicated in attainment of health and treatment of renal injury and osteoporosis. To test for these benefits, weanling Han:SPRD-cy rats (n=171) with or without kidney disease were randomized to diets made with either corn oil or flaxseed oil and with or without SDG for 12 weeks. In females, weight was lower with the SDG diet. In males fed flaxseed oil, lean mass was higher and fat % was lower. In both sexes, fat % was lower in diseased rats. Bone mineral content (BMC) and density were higher in rats fed flaxseed oil and lower in diseased rats, additionally; BMC was lower in SDG-supplemented females. The benefit of flaxseed oil on body composition is sex specific but the effect on bone mass is not. Lastly, reduced weight due to early rat kidney disease is not due to loss of lean body mass.

Effects of Supplementing Broiler Breeder Diets with Organoselenium Compounds and Polyunsaturated Fatty Acids on Hatchability

The effects of supplementing broiler breeder diets with polyunsaturated fatty acids (PUFA) and organoselenium compounds on fertility, hatchability, and the weight of 1-d-old chicks was assessed. Prepeak (23 wk) and peak (27 wk) production breeders were fed 1 of 4 diets: a wheat-based commercial breeder diet with 55 g/kg of either soybean oil (SO) or fish oil (FO), but no added Se (only that originating from feed ingredients), and each diet with added Se as Sel-Plex (SO + Se, FO + Se). The diets were designed to contain <0.1 mg/kg of Se and about 0.5 mg/kg of Se for the nonsupplemented (no added Se) and the supplemented diets, respectively. The Se concentration of the eggshell of the hatching egg was measured. The concentration of Se, PUFA, and total lipid content of the brain and liver of the 1-d-old chick was determined. The number of fertile eggs increased, embryonic mortality decreased, and hatchability increased as hen age increased from 23 to 27 wk. The Se concentration in the eggshell and the brain and liver of 1-d-old chicks was higher in the high-Se treatments com pared with the concentration in the low-Se treatments. Fish oil inclusion in the breeder diet increased embryonic mortality in wk 3 of incubation and reduced both hatchability and 1-d-old chick weight in hens of both ages. The addition of Se to the FO diets ameliorated some of these adverse effects, because chicks hatched from eggs laid by 23-wk-old breeders of the FO + Se treatment were heavier than those receiving the FO treatment. The Se concentration in the brain and liver of chicks from the FO hens was higher than that in chicks from the SO hens. The concentration of docosahexaenoic fatty acid was higher in the liver of chicks from the SO + Se treatment compared with that of chicks from the SO treatment, indicating possible protective effects of Se. Hatchability was decreased by increased PUFA and was higher in 27-wk-old compared with 23-wk-old breeders.

Body size related adaptations of the avian myocardial phospholipid fatty acyl chain composition

The myocardial phospholipid fatty acid (FA) composition (mol %) of 7 avian species was determined, in a body mass range from 150 g (Japanese quail, Coturnix coturnix japonica) to 19 kg (turkey, Meleagris gallopavo). Significant allometric increases were found for C16:1 n7 (allometric exponent: B=0.15), C18:1 n7 (B=0.08), C18:1 n9 (B=0.24), C20:1 n9 (B=0.22) and C20:3 n3 (B=0.12); moreover, total monounsaturates (B=0.20) and the sum of n9 FAs (B=0.24) was also positively related to body mass. The total n3 FAs (B=-0.36), and within them C22:5 n3 (B=-0.41) and C22:6 n3 (B=-0.60) showed allometric declines, such as total polyunsaturated fatty acids (PUFA; B=-0.01), unsaturation index (B=-0.03) and mean FA chain length (B=-0.003). Comparing our results with earlier published data on avian skeletal muscle and divergent mammalian tissues, the allometric scaling of the above membrane forming fatty acids seems to be part of a general relationship postulated as the theory "membranes as metabolic pacemakers". In addition, the cardiac muscle malondialdehyde concentration was negatively related to body mass (B=-0.16), referring to a lower level of lipid peroxidation in larger birds, and vice versa, indicating a progressive myocardial lipid peroxidation in smaller-bodied species.

Timing of incorporation of docosahexaenoic acid into brain and muscle phospholipids during precocial and altricial modes of avian development

We investigated the possibilities that the proportion of docosahexaenoic acid (DHA) in phospholipids of brain and skeletal muscle at hatch, and the ontogenetic timing of the DHA accretion spurt in these tissues, might serve as indices of neonatal functional maturity that discriminate between precocial and altricial avian developmental modes. Comparison of the fatty acid profiles of the initial and residual yolks of two free-living altricial species, the swallow (Hirundo rustica) and the sparrow (Passer domesticus), reveals that, in contrast to precocial birds, there is no preferential uptake of DHA from the yolk during embryonic development. At hatch, the proportions of DHA in brain phospholipid (wt.% of fatty acids) of the swallow and sparrow, at 8.1% and 5.0%, respectively, are far lower than the values (16.9-19.6%) reported for non-altricial species. This reflects a marked difference in the timing of the brain DHA accretion spurt, which occurs during the first half of the embryonic period of precocial birds, but is largely delayed until after hatching in the altricial species. By the time of fledging, the proportion of DHA in the swallow brain phospholipid has increased to 14.3%. For non-altricial birds, the brain DHA concentration at hatch shows little interspecies variation, despite major differences in yolk DHA content. The proportions of DHA in leg muscle phospholipid of the newly hatched swallow and sparrow, at 2.9% and 2.5%, respectively, are far lower than the value (6.7%) for the precocial chicken. Again, this relates to differences in developmental timing, with muscle DHA accretion occurring in the first half of the chicken's embryonic period, whereas, in the swallow, this increase is delayed until after hatching. By the time of fledging in the swallow, DHA forms 9.3% of muscle phospholipid fatty acids, equivalent to the level attained in chicken muscle at the mid-embryo stage. The results indicate a clear distinction between altricial and non-altricial avian species in the timing of tissue DHA accretion during development, presumably reflecting differences in neonatal functional maturity.

Role of intestinal flora in the development of allergy

PURPOSE OF REVIEW

The frequency of allergic diseases is increasing worldwide. Experimental and clinical studies have linked a reduced number of early infections to this trend. The gastrointestinal system, which comprises the largest lymphoid tissue and microbial reservoir of the body, has received more attention during the last few years as a potential determiner in the development of atopic disease.

RECENT FINDINGS

Alterations in intestinal microbiota have been detected both in infants suffering from allergic disease and in those later developing the disorder. Delay in the compositional development of and in gut microflora was a general finding in allergic children. In a subsequent study, perinatal administration of lactobacilli halved the later development of atopic eczema during the first 2 years of life. Specific strains of the healthy gut microbiota have been shown to induce the production of IL-10 and transforming growth factor-beta, which possess an important regulative role in the development of allergic type immune response. Probiotics also strengthen gut defence barrier mechanisms and reduce antigen load in the gut. Pattern recognition receptors in intestinal epithelial and antigen-presenting cells have been demonstrated to mediate a continuing dialogue between host and gut microbiota.

SUMMARY

Despite several promising findings, the exact role of gut normal microbiota in the development of allergy remains to be elucidated. For successful interventions, more data concerning a communication between host and specific microbial species are needed.