n-3 Long-chain PUFA reduce allergy-related mediator release by human mast cells in vitro via inhibition of reactive oxygen species

Effects of Dietary Components on Mast Cells: Possible Use as Nutraceuticals for Allergies?

Allergic diseases affect an estimated 30 percent of the world's population. Mast cells (MC) are the key effector cells of allergic reactions by releasing pro-inflammatory mediators such as histamine, lipid mediators, and cytokines/chemokines. Components of the daily diet, including certain fatty acids, amino acids, and vitamins, as well as secondary plant components, may have effects on MC and thus may be of interest as nutraceuticals for the prevention and treatment of allergies. This review summarizes the anti-inflammatory effects of dietary components on MC, including the signaling pathways involved, in in vitro and in vivo models. Butyrate, calcitriol, kaempferol, quercetin, luteolin, resveratrol, curcumin, and cinnamon extract were the most effective in suppressing the release of preformed and de novo synthesized mediators from MC or in animal models. In randomized controlled trials (RCT), vitamin D, quercetin, O-methylated epigallocatechin gallate (EGCG), resveratrol, curcumin, and cinnamon extract improved symptoms of allergic rhinitis (AR) and reduced the number of inflammatory cells in patients. However, strategies to overcome the poor bioavailability of these nutrients are an important part of current research.

Association of Dietary Polyunsaturated Fatty Acid Intake with Allergic Rhinitis in Adults: A Cross-Sectional Study of NHANES 2005-2006

INTRODUCTION

The incidence of allergic rhinitis (AR) is increasing year by year, and the pathogenesis is complex, in which diet may play an important role. The role of polyunsaturated fatty acids (PUFAs) in AR is still controversial. Previous studies have looked at the effects of PUFA during pregnancy, childhood, and adolescence. In this study, we aimed to determine the association between dietary intake of PUFA and AR in adults.

METHODS

We used the NHANES database from 2005 to 2006 to include a total of 4,211 adult subjects. We collected dietary PUFA intake data and information on AR. Logistic regression and restricted cubic spline models were constructed to examine the association between PUFA intake and AR in adults. The t test was used to compare daily PUFA intakes in patients with and without AR.

RESULTS

In the fully adjusted model (OR: 1.016; 95% CI: 1.003; 1.028), PUFA intake was positively correlated with allergic symptoms, hay fever, and AR in adults (p < 0.05). In addition, daily PUFA intake was significantly higher in people with allergic symptoms, hay fever, and AR than in people without the disease (p < 0.01).

CONCLUSIONS

Our results suggest a positive association between dietary PUFA intake and AR in adults to a certain extent. Future studies on dietary PUFA dose will provide new strategies for the prevention and treatment of allergic diseases such as AR related to non-pharmaceutical interventions.

The Role of Diet and Nutrition in Allergic Diseases

Allergic diseases are a set of chronic inflammatory disorders of lung, skin, and nose epithelium characterized by aberrant IgE and Th2 cytokine-mediated immune responses to exposed allergens. The prevalence of allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, has increased dramatically worldwide in the past several decades. Evidence suggests that diet and nutrition play a key role in the development and severity of allergic diseases. Dietary components can differentially regulate allergic inflammation pathways through host and gut microbiota-derived metabolites, therefore influencing allergy outcomes in positive or negative ways. A broad range of nutrients and dietary components (vitamins A, D, and E, minerals Zn, Iron, and Se, dietary fiber, fatty acids, and phytochemicals) are found to be effective in the prevention or treatment of allergic diseases through the suppression of type 2 inflammation. This paper aims to review recent advances in the role of diet and nutrition in the etiology of allergies, nutritional regulation of allergic inflammation, and clinical findings about nutrient supplementation in treating allergic diseases. The current literature suggests the potential efficacy of plant-based diets in reducing allergic symptoms. Further clinical trials are warranted to examine the potential beneficial effects of plant-based diets and anti-allergic nutrients in the prevention and management of allergic diseases.

The Effect of Fish Oil-Based Foods on Lipid and Oxidative Status Parameters in Police Dogs

The synthesis, degradation, and reconstruction of the cell membrane as a metabolic pathway of phospholipids is a constant and dynamic process. Fatty acids as bioactive lipid components of plasma and erythrocyte phospholipids as structural lipids have biological roles in the integrity of cell membranes. Fatty acids, depending on the chain length, the degree of saturation, and the synthesis pathways, can alleviate inflammation and oxidative stress caused by excessive exercise. Considering that changing food intake or diet can influence fatty acid phospholipid metabolism, our study aimed to determine the potential benefits of fish-based diets in working (police) dogs undergoing intensive training concerning bioactive lipids such as fatty acids, phospholipids of plasma, and erythrocytes. Fatty acid esters’ composition of plasma and erythrocyte phospholipids as a bioactive lipids, in addition to markers of oxidative stress and metabolic parameters, were analysed by GC chromatography. The food was well tolerated by all dogs, and the compliance to the diet was high throughout the study. After the treatment with fish-based food, blood glucose, total, and LDL cholesterol levels were significantly reduced, indicating positive biochemical profiles of dogs. Correlations of fatty acid phospholipid compositions between plasma and erythrocytes have shown that both plasma and erythrocytes could represent markers of omega-3 eicosapentaenoic and docosahexaenoic acid intake levels in dogs. Morover, fish-based food supplementation caused a significant reduction in lipid peroxidation markers. The enrichment of dogs’ diets with marine fish could improve oxidative status and improve roles and status of bioactive lipids, such as membrane phospholipids and fatty acids, as its components in plasma and erythrocytes in police dogs exposed to intensive exercise.

The Complex Interplay between Immunonutrition, Mast Cells, and Histamine Signaling in COVID-19

There is an ongoing need for new therapeutic modalities against SARS-CoV-2 infection. Mast cell histamine has been implicated in the pathophysiology of COVID-19 as a regulator of proinflammatory, fibrotic, and thrombogenic processes. Consequently, mast cell histamine and its receptors represent promising pharmacological targets. At the same time, nutritional modulation of immune system function has been proposed and is being investigated for the prevention of COVID-19 or as an adjunctive strategy combined with conventional therapy. Several studies indicate that several immunonutrients can regulate mast cell activity to reduce the de novo synthesis and/or release of histamine and other mediators that are considered to mediate, at least in part, the complex pathophysiology present in COVID-19. This review summarizes the effects on mast cell histamine of common immunonutrients that have been investigated for use in COVID-19.

Mast Cell Regulation and Irritable Bowel Syndrome: Effects of Food Components with Potential Nutraceutical Use

Mast cells are key actors in inflammatory reactions. Upon activation, they release histamine, heparin and nerve growth factor, among many other mediators that modulate immune response and neuron sensitization. One important feature of mast cells is that their population is usually increased in animal models and biopsies from patients with irritable bowel syndrome (IBS). Therefore, mast cells and mast cell mediators are regarded as key components in IBS pathophysiology. IBS is a common functional gastrointestinal disorder affecting the quality of life of up to 20% of the population worldwide. It is characterized by abdominal pain and altered bowel habits, with heterogeneous phenotypes ranging from constipation to diarrhea, with a mixed subtype and even an unclassified form. Nutrient intake is one of the triggering factors of IBS. In this respect, certain components of the daily food, such as fatty acids, amino acids or plant-derived substances like flavonoids, have been described to modulate mast cells' activity. In this review, we will focus on the effect of these molecules, either stimulatory or inhibitory, on mast cell degranulation, looking for a nutraceutical capable of decreasing IBS symptoms.

Allergy Modulation by N-3 Long Chain Polyunsaturated Fatty Acids and Fat Soluble Nutrients of the Mediterranean Diet

The Mediterranean diet, containing valuable nutrients such as n-3 long chain poly-unsaturated fatty acids (LCPUFAs) and other fat-soluble micronutrients, is known for its health promoting and anti-inflammatory effects. Its valuable elements might help in the battle against the rising prevalence of non-communicable diseases (NCD), including the development of allergic diseases and other (chronic) inflammatory diseases. The fat fraction of the Mediterranean diet contains bioactive fatty acids but can also serve as a matrix to dissolve and increase the uptake of fat-soluble vitamins and phytochemicals, such as luteolin, quercetin, resveratrol and lycopene with known immunomodulatory and anti-inflammatory capacities. Especially n-3 LCPUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from marine oils can target specific receptors or signaling cascades, act as eicosanoid precursors and/or alter membrane fluidity and lipid raft formation, hereby exhibiting anti-inflammatory properties. Beyond n-3 LCPUFAs, fat-soluble vitamins A, D, E, and K1/2 have the potential to affect pro-inflammatory signaling cascades by interacting with receptors or activating/inhibiting signaling proteins or phosphorylation in immune cells (DCs, T-cells, mast cells) involved in allergic sensitization or the elicitation/effector phase of allergic reactions. Moreover, fat-soluble plant-derived phytochemicals can manipulate signaling cascades, mostly by interacting with other receptors or signaling proteins compared to those modified by fat-soluble vitamins, suggesting potential additive or synergistic actions by applying a combination of these nutrients which are all part of the regular Mediterranean diet. Research concerning the effects of phytochemicals such as polyphenols has been hampered due to their poor bio-availability. However, their solubility and uptake are improved by applying them within the dietary fat matrix. Alternatively, they can be prepared for targeted delivery by means of pharmaceutical approaches such as encapsulation within liposomes or even unique nanoparticles. This review illuminates the molecular mechanisms of action and possible immunomodulatory effects of n-3 LCPUFAs and fat-soluble micronutrients from the Mediterranean diet in allergic disease development and allergic inflammation. This will enable us to further appreciate how to make use of the beneficial effects of n-3 LCPUFAs, fat-soluble vitamins and a selection of phytochemicals as active biological components in allergy prevention and/or symptom reduction.

Specific Polyunsaturated Fatty Acids Can Modulate in vitro Human moDC2s and Subsequent Th2 Cytokine Release

Allergy is becoming a rapidly increasing problem worldwide, and in vitro models are frequently used to study the mechanisms behind the different types of allergic response. The dendritic cell (DC)–T-cell model can be used to study sensitization. However, lipopolysaccharide (LPS) is often used to maturate the DCs, but it gives rise to a DC1 phenotype, whereas Th2-driven inflammatory diseases such as allergy are characterized by the involvement of the DC2 phenotype. Our aim was to create a DC2–T-cell human model (human moDC2s) to study in vitro sensitization and validate the model using polyunsaturated fatty acids (PUFAs) that were previously shown to have immunomodulatory properties. We found that the generated DC2s expressed OX40L and drove naive T-cells into IL-13 production of CD4⁺ effector T-cells. In line with in vivo findings, n−3 long-chain (LC)PUFA docosahexaenoic acid (DHA) effectively decreased the DC2's surface expression of OX40L, as well as the IL-12p40 and IL-23 cytokine production by DC2s and subsequently lowered IL-13 production by DC2-induced effector T-cells. Similar cytokine production effects were found with eicosapentaenoic acid (EPA) and arachidonic acid (AA), whereas linoleic acid (LA) increased OX40L surface expression and subsequent T-cell-derived IL-13/IFNγ ratios, suggesting an increased risk of allergy development. Altogether, these data show that human moDC2s are able to induce Th2-type IL-13 secretion by T-cell differentiated in the presence of these DC2s and that this model can be differentially modulated by PUFAs. These results are in line with previous in vivo studies using PUFAs, indicating that this model may be of use to predict in vivo outcomes.

Docosahexaenoyl ethanolamide mitigates IgE-mediated allergic reactions by inhibiting mast cell degranulation and regulating allergy-related immune cells

Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid mainly found in fish oil. Although several studies have suggested that it can alleviate allergy symptoms, its mechanism of action remains to be elucidated. In the present study, we found that docosahexaenoyl ethanolamide (DHEA), a metabolite of DHA produced in the human body, exerts the anti-allergic activity in vitro and in vivo. DHEA suppressed degranulation of rat basophilic leukemia RBL-2H3 cells and bone marrow-derived mast cells in a dose-dependent manner without cytotoxicity. This occurred due to a decrease in Ca²⁺ influx, which is critical for mast cell degranulation. DHEA also suppressed IgE-mediated passive cutaneous anaphylaxis reaction in mice. In addition, DHEA was demonstrated to lessen an allergic symptom in a mouse model of pollinosis and to alter the production of IgE and cytokines secreted by splenocytes collected from the pollinosis mice. Taken together, this study indicates that DHEA is a promising anti-allergic agent as it inhibits mast cell degranulation and modulates other immune cells.

Effects of Omega-3 Fatty Acids on Immune Cells

Alterations on the immune system caused by omega-3 fatty acids have been described for 30 years. This family of polyunsaturated fatty acids exerts major alterations on the activation of cells from both the innate and the adaptive immune system, although the mechanisms for such regulation are diverse. First, as a constitutive part of the cellular membrane, omega-3 fatty acids can regulate cellular membrane properties, such as membrane fluidity or complex assembly in lipid rafts. In recent years, however, a new role for omega-3 fatty acids and their derivatives as signaling molecules has emerged. In this review, we describe the latest findings describing the effects of omega-3 fatty acids on different cells from the immune system and their possible molecular mechanisms.

Long Chain Polyunsaturated Fatty Acids (LCPUFAs) in the Prevention of Food Allergy

N-3 long chain polyunsaturated fatty acids (LCPUFAs) are considered to possess protective properties for human health by impacting on immunological reactions. An “inflammation-suppressive” effect appears to be the common denominator of the beneficial effects of most of these dietary components which may protect against the development of chronic immune disorders such as (food) allergy. LCPUFAs, especially n-3 LCPUFAs, have been shown to interact with both the sensitization as well as the effector phase in food allergy in pre-clinical models. In this review, we explore the anti-allergic properties of LCPUFAs by providing an overview of clinical, in vivo and in vitro studies. Furthermore, we discuss the susceptibility of LCPUFAs to lipid oxidation and possible strategies to support the efficacy of LCPUFAs in reducing the allergy risk by using additional components with anti-oxidative and anti-inflammatory capacities such as the flavonoid quercetin. Finally, we propose new strategies to prevent (food) allergy using combinations of LCPUFAs and additional nutrients in diets or supplements, and postulate to investigate the use of LCPUFAs in allergic symptom relief.

Role of dietary lipids in food allergy

The prevalence of food allergy is raising in industrialized countries, but the mechanisms behind this increased incidence are not fully understood. Environmental factors are believed to play a role in allergic diseases, including lifestyle influences, such as diet. There is a close relationship between allergens and lipids, with many allergenic proteins having the ability to bind lipids. Dietary lipids exert pro-inflammatory or anti-inflammatory functions on cells of the innate immunity and influence antigen presentation to cells of the adaptive immunity. In addition to modifying the immunostimulating properties of proteins, lipids also alter their digestibility and intestinal absorption, changing allergen bioavailability. This study provides an overview of the role of dietary lipids in food allergy, taking into account epidemiological information, as well as results of mechanistic investigations using in vivo, ex vivo and in vitro models. The emerging link among high-fat diets, obesity, and allergy is also discussed.

Immunomodulating peptides for food allergy prevention and treatment

Among the most promising strategies currently assayed against IgE-mediated allergic diseases stands the possibility of using immunomodulating peptides to induce oral tolerance toward offending food allergens or even to prevent allergic sensitization. This review focuses on the beneficial effects of food derived immunomodulating peptides on food allergy, which can be directly exerted in the intestinal tract or once being absorbed through the intestinal epithelial barrier to interact with immune cells. Food peptides influence intestinal homeostasis by maintaining and reinforcing barrier function or affecting intestinal cell-signalling to nearby immune cells and mucus secretion. In addition, they can stimulate cells of the innate and adaptive immune system while supressing inflammatory responses. Peptides represent an attractive alternative to whole allergens to enhance the safety and efficacy of immunotherapy treatments. The conclusions drawn from curative and preventive experiments in murine models are promising, although there is a need for more pre-clinical studies to further explore the immunomodulating strategy and its mechanisms and for a deeper knowledge of the peptide sequence and structural requirements that determine the immunoregulatory function.

Lipid profiling of polarized human monocyte-derived macrophages

The highly orchestrated transcriptional and metabolic reprogramming during activation drastically transforms the main functions and physiology of human macrophages across the polarization spectrum. Lipids, for example, can modify protein function by acting remotely as signaling molecules but also locally by altering the physical properties of cellular membranes. These changes play key roles in the functions of highly plastic immune cells due to their involvement in inflammation, immune responses, phagocytosis and wound healing processes. We report an analysis of major membrane lipids of distinct phenotypes of resting (M0), classically activated (M1), alternatively activated (M2a) and deactivated (M2c) human monocyte derived macrophages from different donors. Samples were subjected to supercritical fluid chromatography-ion mobility-mass spectrometry analysis, which allowed separations based on lipid class, facilitating the profiling of their fatty acid composition. Different levels of arachidonic acid mobilization as well as other fatty acid changes were observed for different lipid classes in the distinct polarization phenotypes, suggesting the activation of highly orchestrated and specific enzymatic processes in the biosynthesis of lipid signaling molecules and cell membrane remodeling. Thromboxane A2 production appeared to be a specific marker of M1 polarization. These alterations to the global composition of lipid bi-layer membranes in the cell provide a potential methodology for the definition and determination of cellular and tissue activation states.

Dietary n-3 long chain polyunsaturated fatty acids in allergy prevention and asthma treatment

The rise in non-communicable diseases, such as allergies, in westernized countries links to changes in lifestyle and diet. N-3 long chain polyunsaturated fatty acids (LCPUFA) present in marine oils facilitate a favorable milieu for immune maturation and may contribute to allergy prevention. N-3 LCPUFA can suppress innate and adaptive immune activation and induce epigenetic changes. Murine studies convincingly show protective effects of fish oil, a source of n-3 LCPUFA, in food allergy and asthma models. Observational studies in human indicate that high dietary intake of n-3 LCPUFA and low intake of n-6 PUFA may protect against the development of allergic disease early in life. High n-6 PUFA intake is also associated with an increased asthma risk while n-3 LCPUFA may be protective and reduce symptoms. The quality of the marine oil used has impact on efficacy of allergy prevention and several observations link in particular n-3 LCPUFA DHA to allergy suppression. Randomized controlled trials indicate that optimal timing, duration and dosage of n-3 LC-PUFA is required to exert an allergy protective effect. Supplementation during early pregnancy and lactation has shown promising results regarding allergy prevention. However these findings should be confirmed in a larger cohort. Although clinical trials in asthma patients reveal no consistent clinical benefits of n-3 LCPUFA supplementation on lung function, it can suppress airway inflammation. Future food-pharma approaches may reveal whether adjunct therapy with dietary n-3 LCPUFA can improve allergy prevention or immunotherapy via support of allergen specific oral tolerance induction or contribute to the efficacy of drug therapy for asthma patients.

Regulation of Exacerbated Immune Responses in Human Peripheral Blood Cells by Hydrolysed Egg White Proteins

The anti-allergic potential of egg white protein hydrolysates (from ovalbumin, lysozyme and ovomucoid) was evaluated as their ability to hinder cytokine and IgE production by Th2-skewed human peripheral blood mononuclear cells (PBMCs), as well as the release of pro-inflammatory factors and generation of reactive oxygen species from Th1-stimulated peripheral blood leukocytes (PBLs). The binding to IgE of egg allergic patients was determined and the peptides present in the hydrolysates were identified. The hydrolysates with alcalase down-regulated the production of Th2-biased cytokines and the secretion of IgE to the culture media of Th2-skewed PBMCs, and they significantly neutralized oxidative stress in PBLs. The hydrolysates of ovalbumin and ovomucoid with pepsin helped to re-establish the Th1/Th2 balance in Th2-biased PBMCs, while they also inhibited the release of pro-inflammatory mediators and reduced oxidative stress in PBLs treated with inflammatory stimuli. The hydrolysates with alcalase, in addition to equilibrating Th2 differentiation, exhibited a low IgE-binding. Therefore, they would elicit mild allergic reactions while retaining T cell-stimulating abilities, which might correlate with an anti-allergic benefit.

Automodification of PARP and fatty acid-based membrane lipidome as a promising integrated biomarker panel in molecular medicine

AIM

Establishing by statistical analyses whether the analyses of auto-modified poly(ADP-ribose)polymerase and erythrocyte membrane fatty acid composition (Fat Profile(®)), separately or in tandem, help monitoring the physio-pathology of the cell, and correlate with diseases, if present.

PATIENTS & METHODS

Ninety five subjects were interviewed and analyzed blindly. Blood lymphocytes and erythrocytes were prepared to assay poly(ADP-ribose)polymerase automodification and fatty acid based membrane lipidome, respectively.

RESULTS

Poly(ADP-ribose)polymerase automodification levels confirmed their correlation with DNA damage extent, and allowed monitoring disease activity, upon surgical/therapeutic treatment. Membrane lipidome profiles showed lipid unbalance mainly linked to inflammatory states. Statistically both tests were separately significant, and correlated each other within some pathologies.

CONCLUSION

In the laboratory routine, both tests, separately or in tandem, might be a preliminary and helpful step to investigate the occurrence of a given disease. Their combination represents a promising integrated panel for sensible, noninvasive and routine health monitoring.

Increased intake of vegetable oil rich in n-6 PUFA enhances allergic symptoms and prevents oral tolerance induction in whey-allergic mice

Increased intake of vegetable oils rich in n-6 PUFA, including soyabean oil, has been associated with an increase in allergic disease. The present study aimed to determine the effect of an increasing dose of dietary vegetable oil on allergic outcomes in mice. To study this, mice received a 7 v. 10 % soyabean oil diet before and during oral sensitisation with whey or whey hyperimmune serum transfer. Another group of mice received partial whey hydrolysate (pWH) while being fed the diets before oral sensitisation. The acute allergic skin response, serum Ig level, mouse mast cell protease-1 (mMCP-1) concentration and/or splenic T-cell percentages were determined upon whey challenge. When the diets were provided before and during oral sensitisation, the acute allergic skin response was increased in mice fed the 10 % soyabean oil diet compared with the 7 % soyabean oil diet. Whey IgE and IgG1 levels remained unaltered, whereas mMCP-1 levels increased in mice fed the 10 % soyabean oil diet. Furthermore, allergic symptoms were increased in naive mice fed the 10 % soyabean oil diet and sensitised with whey hyperimmune serum. In addition to enhancing the mast cell response, the 10 % soyabean oil diet increased the percentage of activated Th1 and Th2 cells as well as increased the ratios of Th2:regulatory T cells and Th2:Th1 when compared with the 7 % soyabean oil diet. Oral tolerance induction by pWH was abrogated in mice fed the 10 % soyabean oil diet compared with those fed the 7 % soyabean oil diet during pretreatment with pWH. In conclusion, increased intake of soyabean oil rich in n-6 PUFA suppresses tolerance induction by pWH and enhances the severity of the allergic effector response in whey-allergic mice. Dietary vegetable oils rich in n-6 PUFA may enhance the susceptibility to develop or sustain food allergy.

Lipid droplets in activated mast cells - a significant source of triglyceride-derived arachidonic acid for eicosanoid production

Mast cells are potent effectors of immune reactions and key players in various inflammatory diseases such as atherosclerosis, asthma, and rheumatoid arthritis. The cellular defense response of mast cells represents a unique and powerful system, where external signals can trigger cell activation resulting in a stimulus-specific and highly coordinated release of a plethora of bioactive mediators. The arsenal of mediators encompasses preformed molecules stored in cytoplasmic secretory granules, as well as newly synthesized proteinaceous and lipid mediators. The release of mediators occurs in strict chronological order and requires proper coordination between the endomembrane system and various enzymatic machineries. For the generation of lipid mediators, cytoplasmic lipid droplets have been shown to function as a major intracellular pool of arachidonic acid, the precursor for eicosanoid biosynthesis. Recent studies have revealed that not only phospholipids in mast cell membranes, but also triglycerides in mast cell lipid droplets are a substrate source for eicosanoid formation. The present review summarizes current knowledge about mast cell lipid droplet biology, and discusses expansions and challenges of traditional mechanistic models for eicosanoid production.

The impact of diet on asthma and allergic diseases

The incidence of allergic diseases is increasing, both in developed and developing countries, concomitantly with the rise in living standards and the adoption of a 'western lifestyle'. For two decades, the hygiene hypothesis - which proposes that the lack of early childhood exposure to infectious agents increases susceptibility to allergic diseases in later life - provided the conceptual framework for unravelling the mechanisms that could account for the increased incidence of allergic diseases. In this Review, we discuss recent evidence that highlights the role of diet as a key factor influencing immune homeostasis and the development of allergic diseases through a complex interplay between nutrients, their metabolites and immune cell populations. Although further investigations are still required to understand these complex relationships, recent data have established a possible connection between metabolic homeostasis and allergic diseases.

Dietary Marine n-3 PUFAs Do Not Affect Stress-Induced Visceral Hypersensitivity in a Rat Maternal Separation Model

BACKGROUND

Although never evaluated for efficacy, n-3 (ω-3) long-chain polyunsaturated fatty acids (LCPUFAs) are commercially offered as treatment for irritable bowel syndrome (IBS).

OBJECTIVE

This study was designed to investigate, in a mast cell-dependent model for visceral hypersensitivity, whether this pathophysiologic mechanism can be reversed by dietary LCPUFA treatment via peroxisome proliferator-activated receptor γ (PPARG) activation.

METHODS

Maternally separated rats were subjected to hypersensitivity-inducing acute stress at adult age. Reversal was attempted by protocols with tuna oil-supplemented diets [4% soy oil (SO) and 3% tuna oil (SO-T3) or 3% SO and 7% tuna oil (SO-T7)] and compared with control SO diets (7% or 10% SO) 4 wk after stress. The PPARG agonist rosiglitazone was evaluated in a 1 wk preventive protocol (30 mg · kg⁻¹ · d⁻¹). Erythrocytes were assessed to confirm LCPUFA uptake and tissue expression of lipoprotein lipase and glycerol kinase as indicators of PPARG activation. Colonic mast cell degranulation was evaluated by toluidine blue staining. In vitro, human mast cell line 1 (HMC-1) cells were pretreated with rosiglitazone, eicosapentaenoic acid, or docosahexaenoic acid, stimulated with phorbol 12-myristate 13-acetate (PMA) and calcium ionophore or compound 48/80 and evaluated for tumor necrosis factor α (TNF-α) and β-hexosaminidase release.

RESULTS

Stress led to visceral hypersensitivity in all groups. Hypersensitivity was not reversed by SO-T3 or control treatment [prestress vs. 24 h poststress vs. posttreatment area under the curve; 76 ± 4 vs. 128 ± 12 (P < 0.05) vs. 115 ± 14 and 82 ± 5 vs. 127 ± 16 (P < 0.01) vs. 113 ± 19, respectively]. Comparison of SO-T7 with its control showed similar results [74 ± 6 vs. 103 ± 13 (P < 0.05) vs. 115 ± 17 and 66 ± 3 vs. 103 ± 10 (P < 0.05) vs. 117 ± 11, respectively]. Erythrocytes showed significant LCPUFA uptake in the absence of colonic PPARG activation. Rosiglitazone induced increased PPARG target gene expression, but did not prevent hypersensitivity. Mast cell degranulation never differed between groups. Rosiglitazone and LCPUFAs significantly reduced PMA/calcium ionophore-induced TNF-α release but not degranulation of HMC-1 cells.

CONCLUSION

Dietary LCPUFAs did not reverse stress-induced visceral hypersensitivity in maternally separated rats. Although further research is needed, claims concerning LCPUFAs as a treatment option in IBS cannot be confirmed at this point and should be regarded with caution.

Sevoflurane ameliorates intestinal ischemia-reperfusion-induced lung injury by inhibiting the synergistic action between mast cell activation and oxidative stress

Preconditioning with sevoflurane (SEV) can protect against ischemia-reperfusion injury in several organs, however, the benefits of SEV against acute lung injury (ALI), induced by intestinal ischemia-reperfusion (IIR), and the underlying mechanisms remain to be elucidated. The present study was designed to investigate the effects of SEV preconditioning on IIR-mediated ALI and the associated mechanisms in a rat model. Female Sprague-Dawley rats treated with 2.3% SEV or apocynin (AP), an inhibitor of NADPH oxidase, were subjected to 75 min superior mesenteric artery occlusion followed by 2 h reperfusion in the presence or absence of the mast cell degranulator compound 48/80 (CP). SEV and AP were observed to downregulate the protein expression levels of p47^phox and gp91^phox in the lungs of normal rats. IIR resulted in severe lung injury, characterized by significant increases in pathological injury scores, lung wet/dry weight ratio, protein expression levels of p47^phox, gp91^phox and ICAM-1, the presence of hydrogen peroxide, malondydehyde and interleukin-6, and the activity of myeloperoxidase. In addition, significant reductions were observed in the expression of prosurfactant protein C, accompanied by an increase in MC degranulation, demonstrated by significant elevations in the number of mast cells, expression levels of tryptase and the concentration of β-hexosaminidase. These changes were further augmented in the presence of CP. In addition, SEV and AP preconditioning significantly alleviated the above alterations induced by IIR alone or in combination with CP. These findings suggested that SEV and AP attenuated IIR-induced ALI by inhibiting NADPH oxidase and the synergistic action between oxidative stress and mast cell activation.

DHA-rich tuna oil effectively suppresses allergic symptoms in mice allergic to whey or peanut

BACKGROUND

Supplementation with long-chain n-3 polyunsaturated fatty acids (LCPUFAs) has been found to reduce the development of allergic disease.

OBJECTIVE

The aim of this study was to compare the effectiveness of fish oil diets rich in eicosapentaenoic acid (20:5n-3; EPA) or docosahexaenoic acid (22:6n-3; DHA) in suppressing food allergic symptoms.

METHODS

Mice were fed a control diet (10% soybean oil) or fish oil diet rich in EPA (4% soybean oil + 6% EPA oil containing 28.8% EPA and 13.7% DHA) or DHA (4% soybean oil + 6% DHA oil containing 7% EPA and 27.8% DHA), starting 14 d before and for 5 wk during oral sensitization with peanut extract (PE) or whey. Acute allergic skin responses, serum immunoglobulins (Igs), and mucosal mast cell protease-1 (mmcp-1) were assessed. Hyperimmune serum was transferred to naive recipient mice fed the different diets.

RESULTS

The DHA diet effectively reduced the acute allergic skin response compared with the control or EPA diet in PE-allergic mice (control, 159 ± 15, or EPA, 129 ± 8, vs. DHA, 78 ± 7 μm; P < 0.0001 or P < 0.05, respectively). In contrast, both the DHA and EPA diets reduced the allergic skin response in whey allergic mice (control, 169 ± 9, vs. DHA, 91 ± 13, or EPA, 106 ± 14 μm; P < 0.001 or P < 0.01, respectively); however, only the DHA diet reduced mmcp-1 and whey-specific IgE and IgG1. The DHA and EPA diets also reduced the acute skin response in passively immunized mice.

CONCLUSIONS

The DHA-rich fish oil diet reduced allergic sensitization to whey and allergic symptoms in both PE- and whey-allergic mice. These data suggest that DHA-rich fish oil is useful as an intervention to prevent or treat food allergy symptoms.

Eicosapentaenoic acid attenuates cigarette smoke-induced lung inflammation by inhibiting ROS-sensitive inflammatory signaling

Cigarette smoking causes chronic lung inflammation that is mainly regulated by redox-sensitive pathways. Our previous studies have demonstrated that cigarette smoke (CS) activates reactive oxygen species (ROS)-sensitive mitogen-activated protein kinases (MAPKs)/nuclear factor-κB (NF-κB) signaling resulting in induction of lung inflammation. Eicosapentaenoic acid (EPA), a major type of omega-3 polyunsaturated fatty acid, is present in significant amounts in marine-based fish and fish oil. EPA has been shown to possess antioxidant and anti-inflammatory properties in vitro and in vivo. However, whether EPA has similar beneficial effects against CS-induced lung inflammation remains unclear. Using a murine model, we show that subchronic CS exposure for 4 weeks caused pulmonary inflammatory infiltration (total cell count in bronchoalveolar lavage fluid (BALF), 11.0-fold increase), increased lung vascular permeability (protein level in BALF, 3.1-fold increase), elevated levels of chemokines (11.4–38.2-fold increase) and malondialdehyde (an oxidative stress biomarker; 2.0-fold increase) in the lungs, as well as lung inflammation; all of these CS-induced events were suppressed by daily supplementation with EPA. Using human bronchial epithelial cells, we further show that CS extract (CSE) sequentially activated NADPH oxidase (NADPH oxidase activity, 1.9-fold increase), increased intracellular levels of ROS (3.0-fold increase), activated both MAPKs and NF-κB, and induced interleukin-8 (IL-8; 8.2-fold increase); all these CSE-induced events were inhibited by pretreatment with EPA. Our findings suggest a novel role for EPA in alleviating the oxidative stress and lung inflammation induced by subchronic CS exposure in vivo and in suppressing the CSE-induced IL-8 in vitro via its antioxidant function and by inhibiting MAPKs/NF-κB signaling.

Immunomodulation of mast cells by nutrients

In the past decades an increasing prevalence of allergic disorders was observed in industrialized countries. Thus, it is necessary to develop adequate therapeutic and preventive strategies. Many of the conservative strategies possess diverse harmful side effects. Therefore agents with fewer side effects and a better compliance among afflicted patients would be of interest. Especially substances with natural origin acting immunomodulatory on mast cells - the key effector cells of allergic diseases - could be used. Among them there are components of the daily diet such as distinct fatty acids and amino acids as well as a range of secondary plant substances such as carotenoids, flavonoids and spices. These nutritional substances could be applied as nutraceuticals in the therapy of mast cell associated diseases. Many of these substances show inhibitory influences on the release of prestored mast cell mediators such as histamine or de novo expression of mast cell mediators such as cytokines and eicosanoids which are involved in the pathogenesis of mast cell associated inflammatory conditions like allergic reactions.

Effects of parental omega-3 fatty acid intake on offspring microbiome and immunity

The "Western diet" is characterized by increased intake of saturated and omega-6 (n-6) fatty acids with a relative reduction in omega-3 (n-3) consumption. These fatty acids can directly and indirectly modulate the gut microbiome, resulting in altered host immunity. Omega-3 fatty acids can also directly modulate immunity through alterations in the phospholipid membranes of immune cells, inhibition of n-6 induced inflammation, down-regulation of inflammatory transcription factors, and by serving as pre-cursors to anti-inflammatory lipid mediators such as resolvins and protectins. We have previously shown that consumption by breeder mice of diets high in saturated and n-6 fatty acids have inflammatory and immune-modulating effects on offspring that are at least partially driven by vertical transmission of altered gut microbiota. To determine if parental diets high in n-3 fatty acids could also affect offspring microbiome and immunity, we fed breeding mice an n-3-rich diet with 40% calories from fat and measured immune outcomes in their offspring. We found offspring from mice fed diets high in n-3 had altered gut microbiomes and modestly enhanced anti-inflammatory IL-10 from both colonic and splenic tissue. Omega-3 pups were protected during peanut oral allergy challenge with small but measurable alterations in peanut-related serologies. However, n-3 pups displayed a tendency toward worsened responses during E. coli sepsis and had significantly worse outcomes during Staphylococcus aureus skin infection. Our results indicate excess parental n-3 fatty acid intake alters microbiome and immune response in offspring.