Is the origin of atopy linked to deficient conversion of omega-6-fatty acids to prostaglandin E1?

Biomarkers identification by a combined clinical and metabonomics analysis in Henoch-Schonlein purpura nephritis children

Background

In children with Henoch-Schonlein purpura (HSP), the severity of Henoch-Schonlein purpura nephritis (HSPN) is considered responsible for the prognosis of HSP. The pathological process from HSP to HSPN is not clear yet and current diagnostic tools have shortcomings in accurate diagnosis of HSPN. This study aims to assess clinical characteristics of HSP and HSPN, to identify metabolic perturbations involved in HSP progress, and to combine metabolic biomarkers and clinical features into a better prediction for HSPN.

Methods

A total of 162 children were recruited, including 109 HSP patients and 53 healthy children (HC). The clinical characteristics were compared between HSPN and HSP without nephritis (HSPWN). The serum metabonomics analysis was performed to determine the metabolic differences in HSP and HC.

Results

Among 109 HSP children, 57 progressed to HSPN. The increased D-dimer level was significantly associated with renal damage in HSP. The metabonomic profiles revealed alterations between various subgroups of HSP and HC, making it possible to investigate small-molecule metabolites related to the pathological process of HSP. In total, we identified 9 biomarkers for HSP vs. HC, 7 for HSPWN vs. HC, 9 for HSPN vs. HC, and 3 for HSPN vs. HSPWN.

Conclusions

(S)-3-hydroxyisobutyric acid, p-Cresol sulfate, and 3-carboxy-4-methyl-5-pentyl-2-furanpropanoic acid were found associated with the progress of HSP to HSPN. Moreover, resulting biomarkers, when combined with D-dimer, allowed improving the HSPN prediction with high sensitivity (94.7%) and specificity (80.8%). Together these findings highlighted the strength of the combination of metabonomics and clinical analysis in the research of HSP.

Chronic enteropathy and feeding in children: an update

Enteropathy defines abnormalities of the small intestinal mucosa of various etiologies in which nutrition has a causal or a therapeutic role. Breast milk is the gold-standard feeding during infancy for optimal nutrition in health and the majority of diseases. Therapeutic formulae have decreased the need for enteral or parenteral support. Gastrointestinal infections are worldwide the most frequent cause of enteropathy by increasing mucosal permeability, local expression of costimulatory molecules allowing antigen penetration in the mucosa, and T-cell activation leading sometimes to disruption of oral tolerance. Concomitant malnutrition impairs not only the immunologic response but also the recovery of damaged mucosa with secondary intestinal and pancreatic enzymatic reductions. Optimal nutritional rehabilitation is the cornerstone of the management of persisting diarrhea. Celiac disease and cow's milk protein allergy are examples of chronic enteropathy. Multiple food allergies, even during breast-feeding, are increasingly reported due to an impaired development of oral tolerance. The dietary approach to allergic disease is currently evolving from passive allergen avoidance to active modulation of the immune system to (re)establish tolerance. The gastrointestinal flora provides maturational signals for the lymphoid tissue, improves balance of inflammatory cytokines, reduces bacterial invasiveness and dietary antigen load, and normalizes gut permeability. The clinical effects of nucleotides and zinc merit further clinical evaluation. Major attention has recently focused on the immune effects of dietary lipids in terms of possible prevention of allergic sensitization by downregulating inflammatory response and protecting the epithelial barrier and host-microbe interactions modifying the adherence of microbes to the mucosa.

Clinical effects of undershirts coated with borage oil on children with atopic dermatitis: a double-blind, placebo-controlled clinical trial

It has been reported that gamma-linolenic acid contained in borage oil is effective against atopic dermatitis. The clinical effects of undershirts coated with borage oil rich in gamma-linolenic acid on atopic dermatitis were evaluated. Thirty-two children, aged 1-10 years, were involved in the clinical control study. Sixteen had worn undershirts coated with borage oil everyday for 2 weeks, and 16 had worn non-coated undershirts as a placebo. Their symptoms were assessed on a 4-point scale. Those children who had worn undershirts coated with borage oil for 2 weeks showed improvements in their erythema and itch, which were statistically significant. Transepidermal water loss from the back was decreased. In the placebo group, there were no statistically significant differences. The undershirts coated with borage oil were found to be statistically effective, and had no side-effects on children with mild atopic dermatitis.

Linoleic acid metabolite levels and transepidermal water loss in children with atopic dermatitis

BACKGROUND

It has been suggested that atopic dermatitis (AD) is associated with impaired delta-6 desaturase activity and the subsequent altered composition of n-6 essential fatty acids (EFAs).

OBJECTIVE

To investigate whether n-6 EFA deficiency accounts for AD by affecting transepidermal water loss or the immune response.

METHODS

Serum levels of n-6 EFAs were measured using gas chromatography-mass spectrometry in a well-defined group of 35 children with AD (IgE level >150 U/mL); 35 age-matched children with allergic rhinitis, asthma, or both (IgE level >150 U/mL); and 31 nonatopic controls (IgE level <100 U/mL). Skin barrier function was evaluated by measuring transepidermal water loss and severity of AD by computing the Scoring Atopic Dermatitis (SCORAD) index.

RESULTS

Atopic children had higher levels of linoleic acid (LA) and lower levels of its metabolites. Furthermore, gamma-linolenic acid to LA and dihommo-gamma-linolenic acid to LA ratios were significantly reduced in atopic patients. Transepidermal water loss and the SCORAD index were negatively correlated with serum levels of LA metabolites. There was no correlation between the SCORAD index and IgE level (P = .51) or between n-6 EFA concentrations and IgE level (P > .10).

CONCLUSIONS

Deficits in n-6 EFAs were correlated with the severity of AD by affecting skin barrier function and cutaneous inflammation. The link between impaired n-6 EFA metabolism and IgE level could not be defined.

Skin barrier function, epidermal proliferation and differentiation in eczema

Skin permeability barrier function is impaired in eczema, particularly in contact and atopic dermatitis (AD). In contact dermatitis disruption of the barrier by irritants and allergens is the primary event, followed by sensitization, inflammation, increased epidermal proliferation and changes in differentiation. Genetically impaired skin barrier function is already present in non-lesional and more pronounced in lesional skin in AD. Increased epidermal proliferation and disturbed differentiation, including changes in lipid composition, cause impaired barrier function in AD. Defective permeability barrier function enables the enhanced penetration of environmental allergens into the skin and initiates immunological reactions and inflammation. Barrier dysfunction is therefore crucially involved in the pathogenesis of AD. The atopic syndrome represents a genetically impaired skin barrier function as well as impaired nasal, bronchial, and intestinal mucous membranes leading to AD, allergic rhinitis, bronchial asthma or aggravation of AD. Common treatment strategies for eczema include the application of lipid-based creams and ointments, which aim toward the restoration of the defective permeability barrier, thus helping to normalize proliferation and differentiation.

Intervention during pregnancy and allergic disease in the offspring

The etiology of allergy is multifactorial, with many variables contributing to the final expression of atopic disease. Three breeding grounds are needed to develop allergic disease: the appropriate genetic background, contact with the allergen(s) and environmental factors. Timing and dosing of allergen(s) are of major importance. Contact with (dietary) allergens and various agents such as tobacco smoke and infections occur not only during post-natal life, but also perinatally and even pre-natally. A critical review of published evidence regarding the impact of maternal exposure to antigens during pregnancy on later development of allergy in the offspring can only conclude that more research is urgently needed. Contact with multiple dietary allergens should be in general of benefit to the fetus to develop tolerance. Current knowledge suggests that pregnant women should have a normal diversified diet, avoiding toxic agents such as tobacco and alcohol. The role of maternal intake of poly-unsaturated fatty acids on the development of atopy in the infants needs to be further evaluated. If parental history would be insufficient to determine the fetal risk, preventive measurements would be advisable for all fetuses.

Impaired sphingomyelinase activity and epidermal differentiation in atopic dermatitis

A defective permeability barrier leads to the penetration of environmental allergens into the skin and initiates immunological reactions and inflammation crucially involved in the pathogenesis of atopic dermatitis (AD). Decreased stratum corneum ceramide content may cause the defect in permeability barrier function consistently found in AD. Acid and neutral sphingomyelinase (A- and N-SMase) generate ceramides with structural and signal transduction functions in epidermal proliferation and differentiation. We determined epidermal SMase activities, DNA synthesis, involucrin, loricrin, filaggrin, and keratin expression in lesional and non-lesional skin of AD patients. We found decreased epidermal A-SMase activity in lesional and non-lesional skin, correlating with reduced stratum corneum ceramide content and disturbed barrier function. N-SMase activity was reduced in non-lesional skin and more significantly reduced in lesional skin, correlating with impaired expression of cornified envelope proteins and keratins, important for skin barrier function. Changes in involucrin, loricrin, filaggrin, keratin K 5 (basal) and K 16 (proliferation associated) were noticed in non-lesional and lesional skin, whereas changes in K 10 (suprabasal), K 6 (proliferation associated), and K 17 (inflammation associated) were found only in lesional skin. In summary, reduction in SMase-generating ceramides and impaired differentiation are involved in the defective barrier function found in AD.

Complementary therapy for atopic eczema and other allergic skin diseases

Atopic eczema is one of the most common chronic inflammatory skin diseases, with a prevalence of at least 10% in children and 0.5-1% in adults. The disease shows a drastically increasing tendency. This article provides an overview of the pathophysiology, pathomechanisms, prevention, and treatment of atopic eczema. We present a therapeutic concept that integrates all aspects of the complex pathophysiology that is a prerequisite for individualized and successful treatment. This is based on intervention in the pathophysiology of atopic eczema and elimination of exogenous provocation factors. Particular attention is given to unconventional therapy options such as phytotherapy, which are attracting patients in many countries, and possible effects, side effects, and interactions with other drugs are discussed.

Fatty acids, the immune response, and autoimmunity: a question of n-6 essentiality and the balance between n-6 and n-3

The essentiality of n-6 polyunsaturated fatty acids (PUFA) is described in relation to a thymus/thymocyte accretion of arachidonic acid (20:4n-6, AA) in early development, and the high requirement of lymphoid and other cells of the immune system for AA and linoleic acid (1 8:2n-6, LA) for membrane phospholipids. Low n-6 PUFA intakes enhance whereas high intakes decrease certain immune functions. Evidence from in vitro and in vivo studies for a role of AA metabolites in immune cell development and functions shows that they can limit or regulate cellular immune reactions and can induce deviation toward a T helper (Th)2-like immune response. In contrast to the effects of the oxidative metabolites of AA, the longer-chain n-6 PUFA produced by gamma-linolenic acid (18:3n-6, GLA) feeding decreases the Th2 cytokine and immunoglobulin (Ig)G1 antibody response. The n-6 PUFA, GLA, dihomo-gamma-linolenic acid (20:3n-6, DHLA) and AA, and certain oxidative metabolites of AA can also induce T-regulatory cell activity, e.g., transforming growth factor (TGF)-beta-producing T cells; GLA feeding studies also demonstrate reduced proinflammatory interleukin (IL)-1 and tumor necrosis factor (TNF)-alpha production. Low intakes of long-chain n-3 fatty acids (fish oils) enhance certain immune functions, whereas high intakes are inhibitory on a wide range of functions, e.g., antigen presentation, adhesion molecule expression, Th1 and Th2 responses, proinflammatory cytokine and eicosanoid production, and they induce lymphocyte apoptosis. Vitamin E has a demonstrable critical role in long-chain n-3 PUFA interactions with immune functions, often reversing the effects of fish oil. The effect of dietary fatty acids on animal autoimmune disease models depends on both the autoimmune model and the amount and type of fatty acids fed. Diets low in fat, essential fatty acid deficient (EFAD), or high in long-chain n-3 PUFA from fish oils increase survival and reduce disease severity in spontaneous autoantibody-mediated disease, whereas high-fat LA-rich diets increase disease severity. In experimentally induced T cell-mediated autoimmune disease, EFAD diets or diets supplemented with long-chain n-3 PUFA augment disease, whereas n-6 PUFA prevent or reduce the severity. In contrast, in both T cell- and antibody-mediated autoimmune disease, the desaturated/elongated metabolites of LA are protective. PUFA of both the n-6 and n-3 families are clinically useful in human autoimmune-inflammatory disorders, but the precise mechanisms by which these fatty acids exert their clinical effects are not well understood. Finally, the view that all n-6 PUFA are proinflammatory requires revision, in part, and their essential regulatory and developmental role in the immune system warrants appreciation.

Nutritional skin care: health effects of micronutrients and fatty acids

Human skin is continuously exposed to internal and external influences that may alter its condition and functioning. As a consequence, the skin may undergo alterations leading to photoaging, inflammation, immune dysfunction, imbalanced epidermal homeostasis, or other skin disorders. Modern nutritional science is developing new insights into the relation between food intake and health, and effects of food ingredients may prove to be biologically relevant for optimal skin condition. The objective of this review was to evaluate the present knowledge about the interrelation of nutrients and skin, particularly the photoprotective effects of nutrients, the influences of nutrients on cutaneous immune responses, and therapeutic actions of nutrients in skin disorders. The nutrients of focus were vitamins, carotenoids, and polyunsaturated fatty acids. Supplementation with these nutrients was shown to provide protection against ultraviolet light, although the sun-protection factor was relatively small compared with that of topical sunscreens. An increase in delayed-type hypersensitivity skin responses after supplementation with nutrients has proven beneficial, especially in elderly people, and may boost cell-mediated immunity. Dietary consumption of certain plants or fish oil is known to modulate the balance of lipid inflammatory mediators and, therefore, is valuable in the treatment of inflammatory skin disorders. It was concluded that nutritional factors exert promising actions on the skin, but information on the effects of low-to-moderate doses of nutrients consumed long term by healthy individuals is obviously lacking, as are data on direct effects on basal skin properties, including hydration, sebum production, and elasticity.

Essential fatty acid metabolism and its modification in atopic eczema

Research from the 1930s to the 1950s established that a deficit of n-6 essential fatty acids (EFAs) leads to an inflammatory skin condition in both animals and humans. In a common inherited skin condition, atopic dermatitis (eczema), there was evidence of low blood EFA concentrations and of a therapeutic response to exceptionally high doses of linoleic acid. More recently, it has been established that there is no deficit of linoleic acid in atopic eczema. Concentrations of linoleic acid instead tend to be elevated in blood, milk, and adipose tissue of patients with atopic eczema, whereas concentrations of linoleic acid metabolites are substantially reduced. This suggests reduced conversion of linoleic acid to gamma-linolenic acid (GLA). In most but not all studies, administration of GLA has been found to improve the clinically assessed skin condition, the objectively assessed skin roughness, and the elevated blood catecholamine concentrations of patients with atopic eczema. Atopic eczema may be a minor inherited abnormality of EFA metabolism.

Double-blind, multicentre analysis of the efficacy of borage oil in patients with atopic eczema

Although gamma-linolenic acid (GLA) has been shown to correct deficiencies in skin lipids associated with reduced delta-6-desaturase activity which should result in improvement of dysregulation of inflammation and immunity in atopic eczema, clinical studies with evening primrose oil containing 10% GLA have yielded contradictory results. We have therefore examined the effect of a higher percentage (at least 23%) GLA-containing borage oil in adults with stable atopic eczema of moderate severity in a double-blind, multicentre study. One hundred and sixty patients were randomized to take daily either 500 mg of borage oil-containing capsules or the bland lipid miglyol as a placebo over a 24-week period. Use of topical diflucortolone-21-valerate cream was allowed as rescue medication, with the amount used until response being defined as primary, and clinical improvement as secondary efficacy criteria. Although several clinical symptoms improved compared with placebo, the overall response to borage oil did not reach statistical significance. Significant differences in favour of borage oil were, however, observed in a subgroup excluding patients who failed to show increased erythrocyte dihomo-gamma-linolenic acid levels and in whom adherence to inclusion criteria and the study protocol were questionable. GLA metabolites increased in borage oil-treated patients only, and serum IgE showed a trend to decrease on overall and subgroup analysis. No substance-related adverse effects were observed. This study shows no overall efficacy of GLA-containing borage oil in atopic eczema, with steroid use being the primary response parameter, although it suggests that a subgroup of patients may benefit from this well-tolerated treatment.

(n-6)-Fatty acids in plasma lipids of children with atopic bronchial asthma

It has been suggested that atopy is associated with an impairment in the delta 6-desaturation of (n-6)-polyunsaturated fatty acids and subsequently low levels of eicosanoid precursors. To evaluate this hypothesis we analyzed the fatty acid composition of plasma phospholipids and plasma cholesterol esters in a well-defined group of children with atopic bronchial asthma (n = 17) and age-matched healthy controls (n = 10). Atopic children showed significantly higher levels of linoleic acid and lower proportions of arachidonic acid in plasma lipids. No differences were observed with respect to gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DHLA). It is concluded that there is no biochemical evidence for a delta 6-desaturation defect in atopic children and therefore no justification for the supplementation of GLA and DHLA; e.g., by the use of evening primrose oil preparations.

Analysis of polyunsaturated fatty acids in newborn sera: a screening tool for atopic disease?

It has been demonstrated that patients with atopic disease have anomalies of fatty acid composition, as a result of altered metabolism or abnormal incorporation of fatty acids into the tissues. In the present study, in 57 newborns 'at risk' for atopic disease, the polyunsaturated fatty acid (PUFA) levels were found to be lower in cord blood in infants who subsequently developed atopic disease than in non-atopics. In all babies, levels of arachidonic acid and dihomo-gamma-linolenic acid in sera at 1 and 3 months of age were lower than those in cord blood. These changes were more marked in children who subsequently developed atopic disease, and in those who, independently of signs and/or symptoms of atopic disease, were formula-fed. A comparison between IgE and PUFA levels revealed no significant differences at any tested time interval. In conclusion, our data suggest that in children 'at risk' for atopy, PUFA levels may be predictive of atopic disease.

Diet and dermatology. The role of dietary manipulation in the prevention and treatment of cutaneous disorders

The role of dietary manipulation and vitamins in the prevention and treatment of certain skin diseases is reviewed. Manipulation of nutrition by either diet restriction or supplementation can effect cutaneous disorders such as skin cancer, wound healing, atopic dermatitis, psoriasis, and dermatitis herpetiformis.

The esterified plasma fatty acid profile is altered in early HIV-1 infection

Previous studies have shown that alterations in micronutrient utilization occur in patients with Acquired Immune Deficiency Syndrome. In this study, total plasma fatty acid composition was measured in 36 homosexual men infected with the Human Immunodeficiency Virus 1 (HIV-1) and in 17 HIV-1 seronegative homosexual men in order to evaluate differences associated with early HIV-1 infection. Immunologic assessment included CD4 cell number count and lymphocyte blastogenesis in response to the mitogens phytohemagglutinin (PHA) and pokeweed (PWM). The mean total amount of omega 6 polyunsaturated fatty acids (18:2 and 20:4) was significantly lower in the HIV-1 seropositive subjects (38 +/- 8.1% SD) as compared to HIV-1 seronegative subjects (43 +/- 4.2%; P = 0.0027). This was also reflected in a higher level of total saturated fatty acids (16:0 and 18:0) in HIV-1 seropositive subjects (30 +/- 2.2% vs. 26 +/- 2.8%; P = 0.0001). The ratio of linoleic to arachidonic acid (18:2 to 20:4) was higher in the HIV-1 seropositive group (6.76 +/- 4.88) compared to the HIV-1 seronegative group (4.86 +/- 1.37; P = 0.0213). The response to PHA in seropositive subjects correlated inversely with total plasma omega 6 fatty acids (r = -0.36; P = 0.027), and directly with the 18:2 to 20:4 ratio (r = 0.33; P = 0.046). CD4 cell counts and the response to PWM did not correlate with plasma fatty acid levels in HIV-1 seropositive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Is the prevalence of atopic dermatitis increasing?

Several studies have suggested that the prevalence of atopic dermatitis has increased over the last three decades, and similar trends have been reported with asthma and hay fever. However, in common with other 'allergic' disease, the definition and measurement of atopic dermatitis in populations has been fraught with problems and has led to difficulties in separating any real changes in disease prevalence from secular changes in diagnosis. In this article, the evidence surrounding the claims of an increased prevalence of atopic dermatitis is examined, and possible reasons for such a change are suggested.

Characterization of grass pollen reactive T-cell lines derived from lesional atopic skin

Since it has been hypothesized that atopic dermatitis represents a cellular immune reaction to exogenous aeroallergens, we investigated whether lesional skin contains allergen-specific T-cells and which lymphokines they might secrete. Using phytohaemagglutinin or grass pollen for the cloning procedure, we established a series of T-cell lines from the skin of two patients. When rechallenged with the allergen, three out of 12 dermal lines which had been cloned with the pollen extract and three out of 20 epidermal lines cloned with PHA were found to proliferate specifically. With one exception, allergen-specific lines were CD4+, CD8-, alpha/beta receptor +. The reaction pattern to the single components of the grass allergen extract was assessed with the line UH-D3. Further, the proliferative response to Lolium perennis was inhibited by HLA-DR antibody, indicating its dependence on structures of the MHC class II complex. Only one out of four CD4+ allergen-reactive lines secreted considerable interferon-gamma activity but all secreted interleukin-4. The relative predominance of IL-4 points to a possible role of skin-derived T-cells in the synthesis of IgE. The identification of allergen-specific T-cells in lesional skin of patients with atopic dermatitis is consistent with the hypothesis that their dermatitis represents a T-cell-mediated immune reaction.