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Propionibacterium acnes is a number of the resident bacterial flora and resides in sebaceous follicles. Age-related and body-dependent quantitative differences exist, indicating the role of sebum as an important ecological factor for P. acnes. Acne patients demonstrate marked increases in this organism which generates inflammation through a variety of mechanisms.
BACKGROUND: The pathogenesis of androgenic alopecia is not fully understood. A microbial-driven inflammatory reaction abutting on the hair follicles might participate in the hair status anomaly. OBJECTIVE: The aim of our study was to determine if ketoconazole (KCZ) which is active against the scalp microflora and shows some intrinsic anti-inflammatory activity might improve alopecia. METHOD: The effect of 2% KCZ shampoo was compared to that of an unmedicated shampoo used in combination with or without 2% minoxidil therapy. RESULTS: Hair density and size and proportion of anagen follicles were improved almost similarly by both KCZ and minoxidil regimens. The sebum casual level appeared to be decreased by KCZ. CONCLUSION: Comparative data suggest that there may be a significant action of KCZ upon the course of androgenic alopecia and that Malassezia spp. may play a role in the inflammatory reaction. The clinical significance of the results awaits further controlled study in a larger group of subjects.
Chromhidrosis or the production of coloured sweat is a rare clinical finding. A 26-year-old female presented with marked pink staining of her uniform and lingerie. Extractions of clothing, skin surface samples, eccrine sebum, urine and a fast food product were spectrophotometrically analysed to identify the pink staining pigment. Three water-soluble colouring agents have been identified. An eccrine route of excretion probably produced chromhidrosis. An overview is presented.
In humans, the skin is a target tissue for androgen action; hair growth and sebum secretion are under active androgen control. An increased production or metabolism of testosterone, the main active androgen, shows up clinically in dermatological symptoms such as hirsutism, hyperseborrheic acne and alopecia. Polycystic ovary syndrome (PCOS) is the most frequent androgen disorder of ovarian function. PCOS patients have amenorrhea or severe oligomenorrhea, increased testosterone levels and most often enlarged polycystic ovaries on ultrasound examination. In addition, many PCOS patients have a tendency to accumulate abdominal fat and/or to develop obesity. Some also display a particular metabolic pattern including an atherogenic lipid profile, glucose intolerance and an increased fasting insulin level, which is known to be closely linked with an insulin resistant state. Several studies have now reported that PCOS patients show increased incidence of type 2 diabetes and cardiovascular disease. In addition to being a target for androgens the skin has abundant insulin receptors on the keratinocyte surface membrane and acanthosis nigricans is a common symptom of severe insulin resistance among patients with insulin receptor disorders. However, acanthosis nigricans could also be present in PCOS women given evidence of the intensity of their insulin resistance. This presentation will review the mutual relationship between hyperandrogenia and insulin resistance, with particular attention paid to: (1) insulin secretion and insulin sensitivity in PCOS; (2) the complexity of the molecular mechanisms involved in insulin resistance; (3) the paradoxical relationship between insulin resistance and hyperandrogenia; (4) the current genetic studies; and (5) new avenues for long-term treatment of PCOS women.
As the outermost layer of skin, the stratum corneum (SC) is continuously exposed to an oxidative environment, including air pollutants, ultraviolet radiation, chemical oxidants, and aerobic microorganisms. Human SC reveals characteristic antioxidant and protein oxidation gradients with increasing antioxidant depletion and protein oxidation towards the outer layers. SC antioxidants, lipids, and proteins are oxidatively modified upon treatments with ultraviolet A/ultraviolet B, ozone, and benzoyl peroxide. alpha-Tocopherol represents the predominating SC antioxidant with respect to its concentration and its unique susceptibility to the various oxidative challenges tested. In sites rich in sebaceous glands, alpha-tocopherol is physiologically delivered to the surface via secretion of sebum. Oxidative damage in the human SC represents an early pathophysiological event preceding barrier disruption and inflammation in environmentally challenged skin. Furthermore, oxidative gradients in SC proteins may have implications for the process of desquamation in human skin.
There is ample clinical evidence suggesting that the nervous system such as emotional stress can influence the course of acne. We examined possible participation of cutaneous neurogenic factors including neuropeptides, neuropeptide-degrading enzymes and neurotrophic factors, in association with inflammation in the pathogenesis of acne. Immunohistochemical studies revealed that substance P (SP)-immunoreactive nerve fibers were in close apposition to the sebaceous glands, and that neutral endopeptidase (NEP) was expressed in the germinative cells of the sebaceous glands in the skin from acne patients. Nerve growth factor showed immunoreactivity only within the germinative cells. In addition, an increase in the number of mast cells and a strong expression of endothelial leukocyte adhesion molecule-1 on the postcapillary venules were observed in adjacent areas to the sebaceous glands. In vitro, the levels and the expression of stem cell factor by fibroblasts were upregulated by SP. When organ-cultured normal skin specimens were exposed to SP, we observed significant increases in the sizes of the sebaceous glands and in the number of sebum vacuoles in sebaceous cells. Furthermore, supplementation of SP to organ-cultured skin induced expression of NEP, and we demonstrated the subcellular localization of NEP in the endoplasmic reticulum and the Golgi apparatus within the sebaceous germinative cells using preembedding immunoelectron microscopy. These findings suggest that SP may stimulate lipogenesis of the sebaceous glands which may be followed by proliferation of Propionibacterium acnes, and may yield a potent influence on the sebaceous glands by provocation of inflammatory reactions via mast cells. Thus, cutaneous neurogenic factors should contribute to onset and/or exacerbation of acne inflammation.
Acne is a disease that can be seen in the first year of age, early childhood, prepubertal age and puberty. Neonatal acne is due mainly to considerable sebum excretion rate, and infantile acne because of high androgens of adrenal origin in girls and of adrenal and testes in boys. These pathogenic mechanisms are characteristic in these ages. Important factors like early onset of comedones and high serum levels of dehydroepiandrosterone sulfate are predictors of severe or long-standing acne in prepubertal age. Hereditary factors play an important role in acne. Neonatal, nodulocystic acne and conglobate acne has proven genetic influences. Postadolescent acne is related with a first-degree relative with the condition in 50% of the cases. Chromosomal abnormalities, HLA phenotypes, polymorphism of human cytochrome P-450 1A1 and MUC1 gene are involved in the pathogenesis of acne. Several other genes are being studied.
Hypercornification is an early feature of acne and usually precedes inflammation. It is associated with ductal hyperproliferation, and there are many controlling factors such as androgens, retinoids, sebum composition and cytokines. Cycling of normal follicles and of comedones may explain the natural resolution of comedones and, in the longer term, resolution of the disease itself. There is a need to tailor treatment according to comedonal type. Suboptimal therapy can often result from inappropriate assessments of comedones, especially microcomedones, sandpaper comedones, submarine comedones and macrocomedones. Macrocomedones can produce devastating acne flares, particularly if patients are inappropriately prescribed oral isotretinoin. Gentle cautery under topical local anaesthesia is a useful therapy in the treatment of such lesions. The newer retinoids and new formulations of all-trans-retinoic acid show a better benefit/risk ratio.
Acne is a multifactorial disease of the pilosebaceous follicle. The most significant pathogenetic factors of acne are: abnormal ductal keratinization, increased sebum secretion, abnormalities of the microbial flora and inflammation. The pilosebaceous unit is an immunocompetent organ. Keratinocytes and sebocytes may act as immune cells capable of pathogen recognition and abnormal lipid presentation, and they might have an important role in initiating and perpetuating the activation of both innate and adaptive immune responses. The elements of the skin immune system are involved in the development of both noninflammatory and inflammatory acne lesions.
BACKGROUND: Patients with atopic dermatitis (AD) are well known to be sensitive to irritation from the environment due to the impaired function of the stratum corneum (SC). Electrical current perception threshold (CPT) evaluation quantifies the sensory threshold to transcutaneous electrical stimulation of the sensory nerves. OBJECTIVE: To study the CPT in a noninvasive fashion using Neurometer CPT/C, together with measurements of various functions of the SC. METHODS: We measured the CPT on the flexor forearm and cheek of AD patients and normal individuals. Subsequently, we evaluated the CPT and skin sensitivity to a 30% aqueous solution of lactic acid after the infliction of various mildly disruptive measures on the SC on the flexor forearm of healthy individuals by the following three methods: (1) removal of the superficial sebum with acetone/ether, (2) scarification with a needle and (3) tape stripping of the SC. Finally, we examined the effect of topical applications of emollients such as petrolatum or a moisturizing cream to the scratched skin. RESULTS: AD patients showed a lower barrier function and lower CPT than normal individuals. In subsequent studies conducted in normal individuals, the CPT was found to be inversely correlated with transepidermal water loss (TEWL) levels after tape stripping. However, most of all, the partial superficial scarification with a needle decreased the CPT and increased the lactic acid stinging response. Prolonged removal of lipids from the SC with acetone/ether for 30 min that increased the TEWL levels for only 1 day decreased the high-frequency conductance value for 2 days and the CPT only on the 2nd day after treatment. Topical applications of emollients were effective to prevent the increased sensitivity caused by scratching. CONCLUSIONS: AD patients showed functional abnormalities of the SC and tended to have more sensitive skin on the cheek and flexor forearm than healthy controls. Even focal SC damage caused by superficial cracking may lead to further disruption of the already damaged SC in AD patients, by eliciting scratching and facilitating the permeation of various environmental allergens and also the induction of hypersensitive skin.
The pH of the skin follows a sharp gradient across the stratum corneum (SC), which is suspected to play an important role in controlling the enzymatic activities involved in cellular metabolism and renewal. This gradient is maintained by several systems, such as sweat and sebum secretion and degradation as well as cellular metabolism. At the surface of the skin, what is measured is in fact an apparent skin pH due to extracted material from the SC diffusing into water applied at the surface. pH values recorded at the surface of a semi hydrophobic milieu such as the SC should be interpreted with great caution because it is obvious that hydrogen ions are not in a pure solution at the surface of the skin. For a correct measurement of skin surface pH, it is recommended to follow all practical operating conditions. Care must be taken in identifying the skin site, healthy controls (age, gender, skin type), the time of day of the measurement and the environmental conditions. Also, subjects should receive precise instructions before the test, mainly in terms of hygiene procedure or use of topical products. The interpretation of data should not overlook the fact that even small differences in pH may reflect significant modifications at the molecular level. Although it is usually agreed that the pH of the skin surface may influence the cutaneous microflora, much remains to be learnt about the role of the acid mantle of the skin with regard to defensins and other protective mechanisms.
BACKGROUND: Demodicosis is a chronic skin disease caused by parasitic mites of the genus Demodex. It usually affects the face area causing major esthetical problems. The pathogenesis of demodicosis is not fully understood; however, it is quite apparent that immunological mechanisms mediate its development. OBJECTIVE: The goal of this study was to study the correlation between immunological and immunogenetic data obtained from patients with demodicosis in order to clarify the pathogenesis of Demodex infestation. METHODS: Twenty-five patients with demodicosis and 13 age- and sex-matched healthy subjects participated in the study. The presence of mites was determined by microscopic inspection of sebum gland secretions. The immune response was evaluated by identifying membrane markers of different immune cells using monoclonal antibodies (anti-CD3+, CD4+, CD8+, CD16+, CD20+ and CD95+) while the concentration of IgA, IgM and IgG was measured by simple radial immunodiffusion. The level of circulating immune complexes and total hemolytic complement as well as the preparatory and digestive function of neutrophils and the functional activity of leukocytes were also studied. Patients were typed for HLA A, B, Bw and Cw using the microlymphocytotoxicity method. RESULTS: The comparison between patients with and without the A2 phenotype showed that the latter have lower numbers of CD8+, lower functional activity of leukocytes, higher concentrations of IgA, larger affected skin areas and are more often affected by deep papular and papulopustular forms of demodicosis than those with the A2 phenotype, showing that this allele has a protective role in demodicosis. Patients exhibiting the Cw2 phenotypes were rather susceptible to demodicosis. They showed decreased numbers of CD3+, increased levels of phagocytic activity, higher mite density and severer skin damage as compared to patients lacking Cw2. CONCLUSIONS: The HLA A2 and Cw2 phenotypes have an important diagnostic, prognostic and pathogenetic significance and could play a role in resistance or susceptibility to demodicosis by regulating the end phase of the immune response.
Healthy human skin is regularly colonized by nonpathogenic microorganisms. Bacterial genera isolated are coagulase-negative staphylococci and diphtheroid rods on the skin surface and propionibacteria in the infundibulum of the sebaceous glands. As for fungi, Pityrosporum (Malassezia spp.) is regularly present. The distribution and density of the flora is dependent on age and environmental factors such as sebum secretion, occlusion, temperature and humidity. Odor production in the axilla is related to the activity of aerobic diphtheroids. Antimicrobials may reduce the density of the skin resident flora, but they do not completely eliminate it. While antimicrobials may cause irritant and allergic contact dermatitis, no evidence exists that the use of antimicrobial substances may change the ecology of resident bacteria on the skin thereby leading to the overgrowth of pathogenic bacteria.
The 'acid mantle' of the stratum corneum seems to be important for both permeability barrier formation and cutaneous antimicrobial defense. However, the origin of the acidic pH, measurable on the skin surface, remains conjectural. Passive and active influencing factors have been proposed, e.g. eccrine and sebaceous secretions as well as proton pumps. In recent years, numerous investigations have been published focusing on the changes in the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. The pH of the skin follows a sharp gradient across the stratum corneum, which is suspected to be important in controlling enzymatic activities and skin renewal. The skin pH is affected by a great number of endogenous factors, e.g. skin moisture, sweat, sebum, anatomic site, genetic predisposition and age. In addition, exogenous factors like detergents, application of cosmetic products, occlusive dressings as well as topical antibiotics may influence the skin pH. Changes in the pH are reported to play a role in the pathogenesis of skin diseases like irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. Therefore, the use of skin cleansing agents, especially synthetic detergents with a pH of about 5.5, may be of relevance in the prevention and treatment of those skin diseases.
The fuzzy rat, a genetic mutant between hairless and hairy albino rats, expresses androgen-dependent hypersecretion of sebum and hyperplastic sebaceous glands. Using this model for human acne, we examined the effects of inhibitors of human steroid 5 alpha-reductase isozymes, type I (MK 386) and type II (finasteride), and an androgen receptor blocker (RU58841) on regression of glandular and ductal hyperplasia. The above three agents, 1% weight volume, were dissolved into the vehicle (propylene glycol, alcohol and water) and applied on the backs of peripubertal male rats for 2 months. Control and castrate groups received vehicle alone. At 8 weeks, we examined the size the sebaceous glandular lobules and ducts in split epidermal preparations as well as in frozen sections of skin stained with osmium-potassium dichromate solution. The number of bromodeoxyuridine (BrdU)-positive cells was counted in the glandular lobes in split-skin tissues stained with BrdU immunochemistry. The results revealed that the sizes of both lobes and ducts in castrates were 40-60% smaller than in controls. RU58841 induced glandular and ductal regression equivalent to that in castrates. Finasteride induced a moderate degree of lobular and ductal reduction, whereas MK386 caused only ductal regression. Reduction of BrdU-positive cells in the sebaceous lobes was found in the skin treated with finasteride and RU58841. Serum concentrations of testosterone and dihydrotestosterone showed no significant changes in all drug-treated rats. The weight of the prostatic lobes was reduced significantly in rats treated with finasteride but not by the other two agents. RU58841 effectively counteracted endogenous androgens resulting in a suppression of growth of the sebaceous glands but not the prostate. This rodent model for androgen-dependent hyperplasia of the sebaceous glands is useful for the study of many pharmacological aspects comprising the rate of percutaneous absorption, stability and affinity to target organs of the testing compounds, and selection of adequate vehicle for topical application.
This study was conducted in order to evaluate a possible protective role of seborrheic complexion and a history of acne on the development of basal cell epithelioma (BCE). For this purpose, 77 patients with this tumor were examined and asked to fill out a questionnaire. The questionnaire included demographic data and questions about skin type, eye and hair colors, sun exposure habits and a past history of acne. The nature, number and location of tumors, the texture of skin and acne scars were noted by a physician. A group of 93 age-, sex- and skin-color-matched patients served as controls. The results show a clear relationship between seborrheic features and a lower risk of developing BCE, after controlling for solar exposure using the Mantel-Haenszel summary measure. The same trend was found in patients with a history of acne. Whether ultraviolet light absorption by sebum, an anticancer activity of Propionibacterium acnes or other factors play a protective role against the development of BCE is as yet unclear.
The antiandrogen cyproterone acetate, which is known to suppress sebum production, but is not a standard therapy, was given in combination with tetracycline to 63 young unmarried men who had failed to respond to 6 months' tetracycline therapy alone. Fifty-seven patients responded and the mean time to clearance was 5.2 months' therapy. The main side effects were nodular sub-nipple breast swellings, which occurred in 13 cases (21%). Such side effects were reversible and cleared after 3-4 months following cessation of therapy. Eighty-eight percent of patients relapsed within 3 months of discontinuing therapy.
After cobalt-60 therapy 3 patients developed open and closed comedones in the face corresponding to the treatment fields. Biopsies showed extensive dermal elastotic material. It is suggested that the elastotic fibres may contribute to a change in the supporting function of the dermis and a secondary sebum retention and comedo formation.