New model of a scaling dermatosis: induction of hyperproliferation in hairless mice with eicosa-5,8,11-trienoic acid

The physiological and pathological properties of Mead acid, an endogenous multifunctional n-9 polyunsaturated fatty acid

Mead acid (MA, 5,8,11-eicosatrienoic acid) is an n-9 polyunsaturated fatty acid (PUFA) and a marker of essential fatty acid deficiency, but nonetheless generally draws little attention. MA is distributed in various normal tissues and can be converted to several specific lipid mediators by lipoxygenase and cyclooxygenase. Recent pathological and epidemiological studies on MA raise the possibility of its effects on inflammation, cancer, dermatitis and cystic fibrosis, suggesting it is an endogenous multifunctional PUFA. This review summarizes the biosynthesis, presence, metabolism and physiological roles of MA and its relation to various diseases, as well as the significance of MA in PUFA metabolism.

Milk Fatty Acids Composition Changes According to β-Hydroxybutyrate Concentrations in Ewes during Early Lactation

Simple Summary

Ketosis can occur during the last six weeks of gestation and continue to the early weeks of lactation due to an increase in energy requirement. This condition can cause substantial economic issues because of the decrease in production, the cost of medical management, the loss of the mothers and the lambs. A better knowledge of this disorder and its early diagnosis could make treatment more effective and optimize productivity. The aims of this study were to understand the metabolic status of the early-lactating ewes and to identify biomarkers for precocious diagnosis of subclinical ketosis using gas chromatographic technique. Different relationships were found between milk fatty acids and metabolic status of the ewes. Furthermore, 8 potential biomarkers were determined.

Abstract

Ketosis is a metabolic disease of pregnant and lactating ewes linked to a negative energy balance which can cause different economic losses. The aims of this study were to understand the metabolic status of the early-lactating ewes and to identify biomarkers for early diagnosis of subclinical ketosis. Forty-six Sarda ewes were selected in the immediate post-partum for the collection of the biological samples. A blood sample from the jugular vein was used to determine β-Hydroxybutyrate (BHB) concentrations. Animals were divided into two groups: BHB 0 or healthy group (n = 28) with BHB concentration < 0.86 mmol/L; and BHB 1 or subclinical ketosis (n = 18) with a BHB concentration ≥ 0.86 mmol/L. Ten mL of pool milk were collected at the morning milking for the analyses. The concentration of 34 milk fatty acids was evaluated using gas chromatography. Two biochemical parameters and 11 milk fatty acids of the total lipid fraction presented a p-value ≤ 0.05. The study revealed different relationships with tricarboxylic acid cycle, blood flows, immune and nervous systems, cell functions, inflammatory response, and oxidative stress status. Eight parameters were significant for the receiver operating characteristic (ROC) analysis with an area under the curve greater than 0.70.

Dietary coconut oil ameliorates skin contact hypersensitivity through mead acid production in mice

Coconut oil is used as a dietary oil worldwide, and its healthy effects are recognized by the fact that coconut oil is easy to digest, helps in weight management, increases healthy cholesterol, and provides instant energy. Although topical application of coconut oil is known to reduce skin infection and inflammation, whether dietary coconut oil has any role in decreasing skin inflammation is unknown. In this study, we showed the impact of dietary coconut oil in allergic skin inflammation by using a mouse model of contact hypersensitivity (CHS). Mice maintained on coconut oil showed amelioration of skin inflammation and increased levels of cis-5, 8, 11-eicosatrienoic acid (mead acid) in serum. Intraperitoneal injection of mead acid inhibited CHS and reduced the number of neutrophils infiltrating to the skin. Detailed mechanistic studies unveiled that mead acid inhibited the directional migration of neutrophils by inhibiting the filamentous actin polymerization and leukotriene B₄ production required for secondary recruitment of neutrophils. Our findings provide valuable insights into the preventive roles of coconut oil and mead acid against skin inflammation, thereby offering attractive therapeutic possibilities.

The Toxic Effects and Mechanisms of Nano-Cu on the Spleen of Rats

Research has shown that nano-copper (nano-Cu) can cause damage to the spleen and immune system yet their mechanisms of cytotoxicity are poorly understood. Our aim is to explore the potential immunotoxicity in the spleen of rats after nano-Cu exposure. The results of hematologic parameters, lymphocyte subsets, immunoglobulins, and histopathology indicated that copper obviously changed the immune function of the spleen. The levels of antioxidants (SOD, CAT, GSH-Px), oxidants (iNOS, NO, MDA), and anti-oxidative signalling pathway of Nrf2 (Nrf2 and HO-1) were strongly induced by nano-Cu. The expression of mRNA and protein of pro-/anti-inflammatory (IFN-γ, TNF-α, MIP-1α, MCP-1, MIF, IL-1/-2/-4/-6) cytokines were increased by nano-Cu. The expression of regulatory signal pathways, MAPKs and PI3-K/Akt were activated, which might be involved in the inflammatory responses and immunomodulatory processes of sub-acute nano-Cu exposure. The immune function of the spleen was repressed by nano-Cu induced oxidative stress and inflammation.

Crosstalk among dietary polyunsaturated fatty acids, urolithiasis, chronic inflammation, and urinary tract tumor risk

Based on a consistent bulk of experimental and epidemiologic works, we proposed that abnormal metabolism and/or dietary deprivation of essential polyunsaturated fatty acids by inducing a chronic and subclinical essential fatty acid deficiency (EFAD) in urothelial cell membranes may enhance the risk for urinary tract tumor (UTT) development. This threat may be enhanced by the unusual fact that the fatty-acid profile of the normal urothelium is similar to that reported in EFAD. The risk for UTT may be worsened when coexisting with a low-grade chronic inflammation (LGCI) state induced by urolithiasis or disbalance management of peroxides, free radical molecules, and their quenchers. There is cumulative evidence linking the LGCI of the urinary tract mucosa, calculi, and UTT, due to the long-standing release of promitotic, promutagen, and pro-inflammatory antiapoptotic cytokines in these conditions. The dual role played by pro- and anti-inflammatory eicosanoids and bioactive lipids, cytokines, and the disbalance of lipid peroxidation is discussed, concluding that the moderate, long-standing consumption or dietary supplementation of ω-3 PUFAs may improve the chances of avoiding UTT development.

Malnutrition-associated rash of cystic fibrosis

Rash is a rare presenting sign of cystic fibrosis (CF) complicated by protein-calorie malnutrition. We measured essential fatty acid (EFA) levels in the serum of a 4-month-old girl with an erythematous, desquamating, periorificially accentuated rash in association with malnutrition and her 2-year-old sister who was diagnosed concurrently with CF but had no rash or signs of malnutrition. Both patients had biochemical evidence of EFA deficiency, suggesting that development of the rash is multifactorial. Clinical presentation, management, and possible modes of pathogenesis of the rash are reviewed. Pathogenesis of the rash appears to involve a complex interaction among deficiencies of EFAs, zinc, protein, and possibly copper, leading to disordered prostaglandin metabolism or cytokine production, or free radical-induced damage to cellular membranes due to a lack of nutrient-derived protective antioxidants.

Nutritional deficiency and the skin

Cutaneous changes occur in deficiency states of many nutritional elements: ascorbic acid, retinol, protein-energy, cyanocobalamin, phytonadione (vitamin K), biotin, ribroflavin, pyridoxine, niacin, essential fatty acids, and zinc. There are also inherited disorders of copper, biotin, zinc, and tryptophan metabolism. Cutaneous vitamin D synthesis is inhibited by sunscreen use. The striking skin changes of the glucagonoma syndrome may be related to nutritional pathways.

Multiple topical applications of arachidonic acid to mouse ears induce inflammatory and proliferative changes

The response to daily topical applications of arachidonic acid (0.25-4 mg/ear/day) to the ears of outbred CD-1 mice was monitored. The first application produced erythema, extravasation of plasma proteins resulting in an increase in ear weight, and some neutrophil accumulation (detected histologically and quantified by myeloperoxidase content). The second application produced minimal edema but did cause erythema and a greater accumulation of neutrophils. Subsequent daily application caused erythema, neutrophil accumulation, and an increase in ear weight predominantly due to cell proliferation (epidermis and connective tissue). Daily applications of other unsaturated fatty acids did not match the response induced by arachidonic acid. Mast cell deficient mice (W/Wv) exhibited a smaller edema response to the first dose of arachidonic acid compared to either their wild-type controls or CD-1 mice. In addition, W/Wv mice exhibited a smaller ear weight increase and myeloperoxidase accumulation following eight daily doses of arachidonic acid. However, epidermal proliferation was similar in all the strains of mice tested. These data suggest that the edema caused by the first topical application of arachidonic acid is partly mast cell mediated. Mast cells also appear to be involved in the neutrophil infiltration induced by multiple topical applications, but not in the epidermal proliferation.

Metabolism and function of skin lipids

It is apparent from this review that the skin is an organ displaying a highly active metabolism of PUFA's. It possesses the capacity to biosynthesize, metabolize and interconvert a variety of lipids as outlined in the review. Its inability to desaturate the essential fatty acids underscores the significance of these PUFAs in cutaneous biology. For instance, increases in the concentrations of 20:4n6 as well as certain autacoids are associated with many inflammatory-hyperproliferative dermatoses. However, the origin of 20:4n6, which is found complexed to skin phospholipids, has until recently remained a mystery. Studies undertaken in our laboratory designed to delineate the origin of epidermal 20:4n6, and to elucidate the effects of EFA deficiency and crossover replenishment with dietary oils on epidermal lipid metabolism have demonstrated: (i) that microsomal preparations from rat and guinea pig epidermis lack the capacity to transform 18:2n6 into 18:3n6 (catalyzed by the enzyme delta 6 desaturase) and 20:3n6 into 20:4n6 (catalyzed by the enzyme delta 5 desaturase). This observation implies that 20:4n6, a component of epidermal phospholipids, is biosynthesized elsewhere endogenously and transported to the epidermis for esterification into the phospholipids. In an extension of this work, epidermal microsomal preparations from normal human and diseased human epidermis (clinically uninvolved and involved psoriatic epidermis) were examined in order to determine the activities of the delta 6 and the delta 5 desaturases as well as the elongase, respectively. Our data revealed that normal, uninvolved and involved human epidermal preparations lack the capacity to desaturate 18:2n6 to 18:3n6 and 20:3n6 to 20:4n6. These results are interesting in view of the fact that 20:4n6 metabolites participate in the phlogistic and hyperproliferative processes in psoriasis. It is likely that the increases in the 20:4n6-derived eicosanoids, which are prominent in uninvolved and involved psoriatic skin, are the result of an enhanced epidermal phospholipase A2 activity. The heightened lipase activity would lead to an elevated concentration of free 20:4n6 which, in turn, would result in the reported increase of epidermal eicosanoid levels. (ii) Incubation of 18:3n6 with microsomal preparations from skin specimens from normal, uninvolved and involved psoriatic epidermis revealed the presence of elongase activity capable of converting 18:3n6 into 20:3n6. This activity was markedly elevated (5-fold) in involved hyperproliferative psoriatic preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic effects of columbinic acid and its metabolites on rat skin

Columbinic acid and its cyclooxygenase and lipoxygenase metabolites were applied topically to the skin of essential fatty acid-deficient rats and their transepidermal water loss was measured. Despite the ability of the major lipoxygenase metabolite to reverse the scaly dermatitis, neither metabolite of columbinate was able to normalize the epidermal water loss, but the parent acid lowered the measurements in a dose-dependent fashion. These results indicate that some essential fatty acids have important functions as such, and not merely as precursors for other, biologically active, oxygenated metabolites.

Lipids in the pathogenesis of ichthyosis: topical cholesterol sulfate-induced scaling in hairless mice

Although several abnormalities of lipid metabolism have been associated with abnormal cornification in humans, evidence that these lipids directly provoke abnormal scale is lacking. One recently described example of a lipid abnormality in ichthyosis is absence of the enzyme steroid sulfatase in recessive X-linked ichthyosis (RXLI). This enzyme normally desulfates cholesterol sulfate (CS) and sulfated steroid hormones, including dehydroepiandrosterone sulfate (DHEAS). As a result of this enzyme deficiency, patients with RXLI accumulate CS in their blood and skin. To determine whether sulfated sterols are the specific cause of increased scale, we applied CS, DHEAS, cholesterol, or vehicle alone to the backs of hairless mice. In animals treated with CS, but not with DHEAS or with vehicle, visible scale without erythema appeared after 1 week, peaked at 2 weeks, and then diminished. When the dose of CS was doubled, abnormal scale reappeared and then decreased again. CS-induced scale was reversible, clearing within 3 days of discontinuation of treatment. Because there was no acanthosis, dermal inflammation, abnormal transepidermal water loss, or increased labeling index, it appears that the 3-fold increase in thickness of the stratum corneum in CS-treated animals is due to a direct effect on this layer.