Acids In Sebum Research Articles

CLINICO-MYCOLOGICAL STUDY OF TINEA CAPITIS

Dermatophytes from the genera Trichophyton and Microsporum cause tinea capitis, a supercial fungal infection of the scalp and scalp hair. The fungi that cause the condition might change over time and space. Tinea capitis mostly affects youngsters, though it can sometimes affect adults. Children between the ages of 3 and 14 are the ones who are most likely to develop it . The lack of fatty acids in sebum, which have a fungi-static effect, has been linked to the increased prevalence in prepubertal children. With poor personal hygiene, congestion, and low socioeconomic level, transmission is exacerbated . The species may evolve over time in any location, particularly as new organisms are brought in via immigration. In order to identify the numerous etiological agents, different clinical kinds, research the epidemiological features, and establish the clinico-mycological association of tinea capitis, a study was carried out in our hospital .

Determining the Effect of pH on the Partitioning of Neutral, Cationic and Anionic Chemicals to Artificial Sebum: New Physicochemical Insight and QSPR Model.

Sebum is an important shunt pathway for transdermal permeation and targeted delivery, but there have been limited studies on its permeation properties. Here we report a measurement and modelling study of solute partition to artificial sebum. Equilibrium experiments were carried out for the sebum-water partition coefficients of 23 neutral, cationic and anionic compounds at different pH. Sebum-water partition coefficients not only depend on the hydrophobicity of the chemical but also on pH. As pH increases from 4.2 to 7.4, the partition of cationic chemicals to sebum increased rapidly. This appears to be due to increased electrostatic attraction between the cationic chemical and the fatty acids in sebum. Whereas for anionic chemicals, their sebum partition coefficients are negligibly small, which might result from their electrostatic repulsion to fatty acids. Increase in pH also resulted in a slight decrease of sebum partition of neutral chemicals. Based on the observed pH impact on the sebum-water partition of neutral, cationic and anionic compounds, a new quantitative structure-property relationship (QSPR) model has been proposed. This mathematical model considers the hydrophobic interaction and electrostatic interaction as the main mechanisms for the partition of neutral, cationic and anionic chemicals to sebum.

Fatty acid compositions of triglycerides and free fatty acids in sebum depend on amount of triglycerides, and do not differ in presence or absence of acne vulgaris.

To clarify the influence of the fatty acid composition of sebum in acne vulgaris, we investigated the amounts and fatty acid compositions of triglycerides (TG) and free fatty acids (FFA), and the amounts of cutaneous superficial Propionibacterium acnes in acne patients and healthy subjects. The foreheads of 18 female patients, 10 male patients, 10 healthy females and 10 healthy males were studied in a Japanese population. There were significant differences in the amounts of sebum, TG and cutaneous superficial P.acnes, as well as the fatty acid compositions of TG and FFA between acne patients and healthy subjects in females. Their fatty acid compositions were correlated with the amount of TG with or without acne. It was clarified that the fatty acid compositions of TG and FFA depended on the amount of TG, and there were no differences in the fatty acid composition in the presence and absence of acne.

Tinea Capitis in 31 Year Old Adult Male: A Rare Entity

Tinea capitis also called as ring worm of the hair is a superficial fungal infection (dermatophytosis) of the scalp. The clinical presentation is typically single or multiple patches of hair loss, sometimes with a 'black dot' pattern (often with broken-off hairs), that may be accompanied by inflammation, scaling, pustules, and itching. Tinea Capitis affects primarily pre-pubertal children between 6 and 10 years, it is more common in males than females; rarely does the disease persist past age sixteen.3 When it occurs in adults the clinical features may be atypical and this may delay the diagnosis. The most common clinical features are severe itching of the scalp, dandruff, and bald patches where the fungus has rooted itself in the skin. It is uncommon in adults, but an immune defect may facilitate hair invasion. Physical barriers such as the intact keratinized layer of skin, as well as the effect of UV light, physiochemical factors of temperature, moisture and pH, and fungistatic fatty acids on the skin play a vital role in resisting contact with the organism. The quantity of fungistatic saturated fatty acids in sebum increases at puberty, and this is thought to explain the rarity of tinea capitis in adults.

Propionibacterium acnes and Sebaceous Lipogenesis: A Love–Hate Relationship?

In this issue, Iinuma et al. show that Propionibacterium acnes (P. acnes)-conditioned medium and formalin-killed P. acnes augment intracellular lipid formation in hamster sebocytes by increasing the de novo synthesis of triacylglycerols. This commentary summarizes the current knowledge of the association of P. acnes with sebaceous lipogenesis, inflammation, and innate immunity, and points out the concurrent evidence that P. acnes-induced lipids may represent a recruitment of allies and/or enemies of the human skin.

The effect of a low glycemic load diet on acne vulgaris and the fatty acid composition of skin surface triglycerides

Dietary factors have long been implicated in acne pathogenesis. It has recently been hypothesized that low glycemic load diets may influence sebum production based on the beneficial endocrine effects of these diets. To determine the effect of a low glycemic load diet on acne and the fatty acid composition of skin surface triglycerides. Thirty-one male acne patients (aged 15-25 years) completed sebum sampling tests as part of a larger 12-week, parallel design dietary intervention trial. The experimental treatment was a low glycemic load diet, comprised of 25% energy from protein and 45% from low glycemic index carbohydrates. In contrast, the control situation emphasized carbohydrate-dense foods without reference to the glycemic index. Acne lesion counts were assessed during monthly visits. At baseline and 12-weeks, the follicular sebum outflow and composition of skin surface triglycerides were assessed using lipid absorbent tapes. At 12 weeks, subjects on the experimental diet demonstrated increases in the ratio of saturated to monounsaturated fatty acids of skin surface triglycerides when compared to controls [5.3+/-2.0% (mean+/-S.E.M.) vs. -2.7+/-1.7%, P=0.007]. The increase in the saturated/monounsaturated ratio correlated with acne lesion counts(r=-0.39, P=0.03). Increased follicular sebum outflow was also associated with an increase in the proportion of monounsaturated fatty acids in sebum (r=0.49, P=0.006). This suggests a possible role of desaturase enzymes in sebaceous lipogenesis and the clinical manifestation of acne. However, further work is needed to clarify the underlying role of diet in sebum gland physiology.

Unsaturated Fatty Acids Induce Calcium Influx into Keratinocytes and Cause Abnormal Differentiation of Epidermis

Abnormal follicular keratinization is involved in comedogenesis in acne vulgaris. We recently demonstrated that calcium influx into epidermal keratinocytes is associated with impaired skin barrier function and epidermal proliferation. Based on these results, we hypothesized that sebum components affect calcium dynamics in the keratinocyte and consequently induce abnormal keratinization. To test this idea, we first observed the effects of topical application of sebum components, triglycerides (triolein), saturated fatty acids (palmitic acid and stearic acid), and unsaturated fatty acids (oleic acid and palmitoleic acid) on hairless mouse skin. Neither triglyceride nor saturated fatty acids affected the skin surface morphology or epidermal proliferation. On the other hand, application of unsaturated fatty acids, oleic acid, and palmitoleic acid induced scaly skin, abnormal keratinization, and epidermal hyperplasia. Application of triglycerides and saturated fatty acids on cultured human keratinocytes did not affect the intracellular calcium concentration ([Ca(2+)](i)), whereas unsaturated fatty acids increased the [Ca(2+)](i) of the keratinocytes. Moreover, application of oleic acid on hairless mouse skin induced an abnormal calcium distribution in the epidermis. These results suggest that unsaturated fatty acids in sebum alter the calcium dynamics in epidermal keratinocytes and induce abnormal follicular keratinization.

Viewpoint 3

Viewpoint 3

Spectral Differences between Stratum Corneum and Sebaceous Molecular Components in the Mid-IR

Despite a number of studies on the composition of the lipids of stratum corneum (SC) and sebum, questions remain about the detailed molecular arrangement of the two superficial components of human skin. The investigation of the molecular components of SC in vivo is important to understand the function of what was once thought to be a “dead” epithelium. We have investigated the molecular composition of SC and sebum in vivo, in the mid-infrared, with fiber-based attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR). This technique combines the sensitivity of infrared spectroscopy in detecting molecular composition and conformational order with the capability of probing surfaces to a depth of less than 1 μm. ATR/FT-IR is therefore particularly useful for the investigation of interfaces such as SC and the sebaceous layers. We found that with the use of ATR/FT-IR one can distinguish between the contribution of the molecular components of sebum and SC. The presence of spectral “signatures” of the lipids of sebum allowed us to improve the interpretation of some infrared bands of sebaceous origin as well as of SC in vivo. We also found that ATR/FT-IR can be used to separate the spectral contributions of sebum and SC, and as a method to study the early recovery of superficial lipids after the removal of sebum. Following calibration, a method can be developed to quantify the relative amount of fatty acid in sebum with the use of ATR/FT-IR. We observed that the sebaceous fatty acids that reach the surface of the skin recover at a slower rate than other sebaceous lipids. Our investigation shows that fiber-based ATR/FT-IR is a promising spectroscopic approach to the study of epithelial surfaces and surface contaminants in vivo.

Fatty acid composition of sebum wax esters and urinary androgen level in normal human individuals

To investigate the effects of androgens on the fatty acid compositions of sebum wax esters, we examined sebum and urinary samples from 36 healthy individuals, aged from 3 to 59 years. The percentages of C 16 : 1 straight chain components in wax esters were correlated positively with the urinary testosterone levels in both sexes, and with the urinary levels of etiocholanolone and total 17-ketosteroids (17-KS) in females. These data suggest that more active sebaceous glands in lipid production excrete sebum with a higher proportion of C 16 : 1 straight chain fatty acid, which is considered to be purely endogenous. It appears, therefore, that the proportion of C 16 : 1 straight chain fatty acid in sebum wax esters may indicate the sebaceous gland activity in both sexes. In comparison of the amounts of various straight and terminally branched fatty acids in sebum with urinary androgen levels, the straight even fatty acids tended to change in a positive correlation with testosterone levels, in contrast to the changes of the iso even fatty acids in both sexes and to those of the iso odd fatty acids in males. The straight odd fatty acids showed a similar change to that of the straight even fatty acids in males, while in females, there was no significant correlation between the amounts of the fatty acids and testosterone levels. Anteiso fatty acids showed no notable change correlated with testosterone levels. This result suggests that the synthesis of iso or anteiso fatty acids may be controlled by complex factors and that there may be a unique source of anteiso fatty acids in human sebaceous glands.

Effect of cyproterone acetate-ethinyl estradiol treatment on the proportions of linoleic and sebaleic acids in various skin surface lipid classes.

The effect of high-dose cyproterone acetate-ethinyl estradiol treatment on rates of sebum secretion and on the proportions of linoleic acid (18:2 delta 9,12) and sebaleic acid (18:2 delta 5,8) in the skin surface lipids of three female acne patients was examined. Changes in rates of sebum secretion were evaluated indirectly by measuring the ratio of wax esters/(cholesterol + cholesterol esters) in the subjects' skin surface lipid. In two of the subjects, this ratio indicated a reduction of sebum secretion rates to the childhood range. Concomitantly, there was an increase in linoleic acid and a decrease in sebaleic acid in all lipid classes. In the third subject, in whom there was only a small reduction in sebum secretion rate, the proportion of linoleic acid in the cholesterol esters more than doubled, but the changes in the other lipid classes were small or nonexistent. The results indicate that the proportions of linoleic acid and sebaleic acid in sebum are influenced by sebum secretion rates.

The effect of oral zinc administration on sebum free fatty acids in acne vulgaris

Free fatty acids in sebum arise from lipolytic action of bacterial lipases. We have demonstrated an inhibitory effect of zinc on the lipase of the three Propionibacterium species found in human pilosebaceous follicles. We were also able to show a small corresponding fall in the free fatty acid content of skin surface lipid in vivo in acne patients treated with zinc, though this failed to reach statistical significance.

Enhanced comedo formation in rabbit ear skin by squalene and oleic acid peroxides.

The comedogenicity of UVA-irradiated and non-irradiated substances (squalene, oleic acid, tetradecane, isopropyl myristate, squalane and liquid paraffin) was evaluated by surface microscopy and histological examination after treating the ventral skin of rabbit ears with these substances. The lipid peroxide levels of these substances were also measured. Squalene itself was scarcely comedogenic but squalene peroxides were highly comedogenic. Both oleic acid and its peroxides were able to induce fairly large comedones and there was a good correlation between the lipid peroxide levels and the size of the comedones. The specimens biopsied from these comedones showed marked hyperplasia and hyperkeratosis of the epithelium in the follicular infundibulum and marked proliferation of the sebaceous glands. Although free fatty acids might play a role in the pathogenesis of acne, it is proposed that squalene and free fatty acids in sebum may be less comedogenic than their peroxides.

Studies on the mechanism of action to topical benzoyl peroxide and vitamin A acid in acne vulgaris.

Although systemic telracycline remains the most frequent treatment for acne vulgaris, this report indicates that more effective antibacterial therapy can be achieved topically. The effective agent, benzoyl peroxide, produced a mild desquamation: while concommitantly reducing the fatty acids in sebum more dramatically than systemic tetracycline. Bacterial cultures demonstrated the potential of this peroxide to inhibit the growth of C. acnes recovered from sebaceous follicles. Since the mechanism of benzoyl peroxide is different than topical vitamin A acid, combination therapy has been evaluated in over 1,000 acne patients. The clearing of acne lesions is now routine in the majority of these cases within the initial three months of therapy.

Acne: pathogenesis and treatment.

Treatment for acne is far from optimal. This is understandable when we consider that the pathogenesis of the disease is still controversial and there are only limited means of controlling the process at different levels. Of the therapeutic agents that are available, benzoyl peroxide and vitamin A acid used in combination have given the best results in the majority of patients. Benzoyl peroxide inhibits the formation of free fatty acids in sebum, and vitamin A acid prevents follicular hyperkeratosis.

The Origin of Free Fatty Acids in Sebum. I. Role of Coagulase Negative Staphylococci

In recent years the constituents of sebum, especially the free fatty acids, have become accepted as a primary factor in the pathogenesis of acne vulgaris (1). Lipolysis of preformed lipids by the lipase and esterase activity of the microbial flora of the skin has been shown to constitute one of the major sources of the free fatty acids of surface lipids (2, 3) although lipolytic activity of non-bacterial origin has not been exlcuded as an additional source of free fatty acids.

Intracutaneous Injection of Sebum and Comedones

The injection of sebum and comedones into the human skin excites a lymphocytic inflammatory response. The free fatty acids in sebum are chiefly responsible for the observed inflammation. When the inflammation is quite marked, the pilosebaceous follicles undergo rupture, and strands of epithelium grow out to encapsulate the inflammatory mass. Giant cells, which may be present in the inflammatory response, appear to be the result of follicular collapse with the consequent liberation of follicular wall keratin and hair which act as foreign bodies. These histological changes are comparable to those occurring in acne.