The chemoattractant properties of comedonal components

Dual Role of Cutibacterium acnes: Commensal Bacterium and Pathogen in Ocular Diseases

Microbiota present around the ocular surface, encompassing the eyelid skin, the conjunctival sac, and the meibomian glands, play a significant role in various inflammatory conditions associated with the ocular surface. Cutibacterium acnes (C. acnes), formerly, Propionibacterium acnes, is one of the most predominant commensal bacteria and its relative abundance declines with aging. However, it can act as both an infectious and an immunogenic pathogen. As an infectious pathogen, C. acnes has been reported to cause late onset endophthalmitis post-cataract surgery and infectious keratitis. On the other hand, it can trigger immune responses resulting in conditions such as phlyctenules in the cornea, chalazion in the meibomian glands, and granuloma formation in ocular sarcoidosis. This review explores the role of C. acnes in ocular inflammation, specifically highlighting its implications for diagnosis and management.

A systematic review of N-acetylcysteine for treatment of acne vulgaris and acne-related associations and consequences: Focus on clinical studies

Acne vulgaris is one of the most common dermatologic disorders affects people of all races and ethnicities and has many adverse effects on the quality of life. The increased bacterial resistance to antibiotics has reduced the effectiveness of treatment with these agents. There is an increasing focus on the involvement of oxidative stress in the pathophysiology of acne. This study investigates the effect of N-acetylcysteine (NAC) as an antioxidant in the treatment of acne vulgaris. This systematic review was conducted through a search in databases such as Science Direct, PubMed, Scielo, and Medline using keywords including acne vulgaris, anti and NAC, and all the keywords associated with each of the subtitles. The factors affecting the occurrence and expansion of acne include increased sebum synthesis, hyperkeratinization of pilosebaceous units, colonization with Propionibacterium acnes, and increased release of inflammatory mediators and ROS. Studies have shown that glutathione stimulation following the administration of NAC increases glutathione levels for the detoxification of oxygen-free radicals. Moreover, NAC prevents the synthesis and release of inflammatory cytokines such as TNF-α, IL-8, IL-6, MP9, and IL-1β and has shown antibacterial activities against important bacteria including E. coli, S. epidermidis, Pseudomonas, and Klebsiella. This medication has anti-proliferative effects and is also used for excoriation and PCOD. The results of the present study showed the beneficial effects of using NAC in patients with acne vulgaris in terms of the disease complications and comorbidities. Given its diverse functional mechanisms, this medication can be used to treat acne and its consequences.

Natural products as mediators of disease

Covering: up to 2016Humans are walking microbial ecosystems, each harboring a complex microbiome with the genetic potential to produce a vast array of natural products. Recent sequencing data suggest that our microbial inhabitants are critical for maintaining overall health. Shifts in microbial communities have been correlated to a number of diseases including infections, inflammation, cancer, and neurological disorders. Some of these clinically and diagnostically relevant phenotypes are a result of the presence of small molecules, yet we know remarkably little about their contributions to the health of individuals. Here, we review microbe-derived natural products as mediators of human disease.

Expert committee recommendations for acne management

In 2003, an international committee of physicians and researchers in the field of acne, working together as the Global Alliance to Improve Outcomes in Acne, developed consensus guidelines for the treatment of acne. These guidelines were evidence based when possible but also included the extensive clinical experience of this group of international dermatologists. As a result of the evaluation of available data and the experience, significant changes occurred in the management routines for acne. The greatest change arose on the basis of improved understanding of acne pathophysiology. The recommendation now is that acne treatments should be combined to target as many pathogenic factors as possible. A topical retinoid should be the foundation of treatment for most patients with acne, because retinoids target the microcomedo, the precursor to all acne lesions. Retinoids also are comedolytic and have intrinsic antiinflammatory effects, thus targeting 2 pathogenic factors in acne. Combining a topical retinoid with an antimicrobial agent targets 3 pathogenic factors, and clinical trials have shown that combination therapy results in significantly faster and greater clearing as opposed to antimicrobial therapy alone. Oral antibiotics should be used only in moderate-to-severe acne, should not be used as monotherapy, and should be discontinued as soon as possible (usually within 8-12 weeks). Because of their effect on the microcomedo, topical retinoids also are recommended as an important facet of maintenance therapy.

Laser therapy for acne

Considered the most common skin disorder, acne affects millions of people every year. This multifactorial condition of the pilosebaceous follicle is a combination of at least four different primary pathogeneses. In recent years, acne therapies have been improving, becoming more effective, and targeting one or more of these causes. Many current therapies have drawbacks involving patient compliance, systemic toxicities, and bacterial resistance. Lasers are now established options in the armamentarium to treat acne. The 532-nm potassium titanyl phosphate laser, 585- and 595-nm pulsed dye lasers, 1450-nm diode laser, and 1540-nm erbium glass laser have been used with variable efficacy. Lasers may be best used in combination with other therapies to enhance their results. Photodynamic therapy has been successful with substances such as 5-aminolevulinic acid and indocyanine green. Lasers remain viable alternatives for people who may not desire or be able to use topical or systemic formulations. Drawbacks associated with lasers include potential pain, skin discoloration, and cost of treatment. Typically, multiple sessions are required to achieve the desired results, with future maintenance treatments possible to maintain the outcomes. With additional clinical trials underway, laser treatment of acne will surely advance and continue to be optimized in the future.

Topical antibacterial treatments for acne vulgaris : comparative review and guide to selection

Topical antibacterial agents are an essential part of the armamentarium for treating acne vulgaris. They are indicated for mild-to-moderate acne, and are a useful alternative for patients who cannot take systemic antibacterials. Topical antibacterials such as clindamycin, erythromycin, and tetracycline are bacteriostatic for Propionibacterium acnes, and have also been demonstrated to have anti-inflammatory activities through inhibition of lipase production by P. acnes, as well as inhibition of leukocyte chemotaxis. Benzoyl peroxide is a non-antibiotic antibacterial agent that is bactericidal against P. acnes and has the distinct advantage that thus far, no resistance has been detected against it. Combined agents such as erythromycin/zinc, erythromycin/tretinoin, erythromycin/isotretinoin, erythromycin/benzoyl peroxide, and clindamycin/benzoyl peroxide are increasingly being used and have been proven to be effective. They generally demonstrate good overall tolerability and are useful in reducing the development of antibacterial resistance in P. acnes. The selection of a topical antibacterial agent should be tailored for specific patients by choosing an agent that matches the patient's skin characteristics and acne type. Topical antibacterial agents should generally not be used for extended periods beyond 3 months, and topical antibacterials should ideally not be combined with systemic antibacterial therapy for acne; in particular, the use of topical and systemic antibacterials is to be avoided as far as possible.

Proinflammatory cytokine production by human keratinocytes stimulated with Propionibacterium acnes and P. acnes GroEL

BACKGROUND

Keratinocytes form the first line of defence in the skin and alert the host to danger by the production of a number of cytokines and chemokines. However, the interaction of commensal microorganisms with keratinocytes has not been well studied.

OBJECTIVES

To investigate the effect of viable and nonviable cells of Propionibacterium acnes in both exponential and stationary growth phases, and of P. acnes GroEL on cytokine production by human primary keratinocytes.

METHODS

Actively proliferating or contact-inhibited keratinocytes were cocultured with viable or formaldehyde-killed P. acnes cells in either the exponential or stationary phase of growth. Culture supernatants were assayed by enzyme-linked immunosorbent assay for the cytokines interleukin (IL)-1alpha, tumour necrosis factor (TNF)-alpha and granulocyte/macrophage colony-stimulating factor (GM-CSF). Keratinocytes were also stimulated with different concentrations of P. acnes GroEL and supernatants assayed for cytokines.

RESULTS

Viable P. acnes in the stationary phase of growth stimulated keratinocyte monolayers to produce significantly higher amounts of IL-1alpha, TNF-alpha and GM-CSF than unstimulated keratinocytes. Viable exponential-phase bacteria stimulated production of significantly higher amounts of TNF-alpha and GM-CSF but these levels were significantly lower than those for stimulation with stationary-phase bacteria. Nonviable P. acnes from either growth phase was not able to stimulate cytokine production. P. acnes GroEL at concentrations in the range 0.05-1.0 micro g mL(-1) was able to induce increased production of cytokines by keratinocytes in a dose-dependent manner. This was analogous to stimulation with Escherichia coli GroEL.

CONCLUSIONS

Stimulation of cytokine production by P. acnes and P. acnes GroEL may be important in the pathogenesis of inflammatory acne vulgaris and may have wider implications for the immunomodulation of the human immune system by commensal skin microorganisms.

Current concepts of the pathogenesis of acne: implications for drug treatment

The pathogenesis of acne is complex, with strong evidence supporting the involvement of sebaceous hyperplasia, follicular hyperkeratinisation, bacterial hypercolonisation, as well as immune reactions and inflammation. High sebum concentrations and follicular hyperkeratinisation lead to a change of the follicular milieu with consecutive proliferation of bacteria, chiefly Propionibacterium acnes. This leads to further increased production of the pro-inflammatory cytokines interleukin-1alpha and tumour necrosis factor alpha by T cells and keratinocytes, leading to proliferation of both cell types. Follicular keratinocytes fail to differentiate by apoptosis and produce hypergranulosis similar to the impermeable skin outer layer, resulting in the formation of microcomedones. Further inflammatory responses lead to the development of increasing degrees of severity in inflammatory forms of acne. Retinoids aid the differentiation and reduce the hyperproliferation of keratinocytes, and can inhibit the migration of leucocytes. Combination therapy using retinoids plus benzoyl peroxide or antibacterials can treat existing acne lesions faster than the individual agents alone and can also prevent the development of new lesions. The new retinoids (e.g. adapalene) have not only the typical potent comedolytic activity but also anti-inflammatory effects. When added to antibacterial therapy, topical retinoids demonstrate faster and significantly greater reduction of inflammatory acne lesions and comedones than antibacterials alone.

Antibacterial therapy for acne: a guide to selection and use of systemic agents

Acne vulgaris is a very common disorder, affecting virtually every adolescent at some point in time. Systemic antibacterials have been used in the treatment of acne for many years, and there are several commonly used antibacterials which have established efficacy and safety records. In recent years, the issue of antibacterials resistance has become more prominent, especially with concerns that Propionibacterium acnes can transfer antibacterials resistance to other bacteria within the resident skin flora. Commonly used antibacterials include tetracycline, doxycycline, minocycline, erythromycin (and other macrolides) and trimethoprim/sulfamethoxazole (cotrimoxazole). The choice of antibacterial should take into account efficacy, cost-effectiveness, benefit-risk ratios, patient acceptability and the potential for the development of resistance. Poor clinical response can be the result of poor compliance, inadequate duration of therapy, development of gram-negative folliculitis, resistance of P. acnes to the antibacterial(s) administered, or a high sebum excretion rate. In order to help prevent the development of resistance a number of measures should be undertaken: antibacterials are prescribed for an average of 6 months; if retreatment is required, utilize the same antibacterial; generally, antibacterials should be given for at least 2 months before considering switching due to poor therapeutic response; concomitant use of oral and topical chemically-dissimilar antibacterials should be avoided (try benzoyl peroxide and/or retinoids instead) and systemic isotretinoin should be considered if several antibacterials have been tried without success.

Increased hydrogen peroxide generation by neutrophils from patients with acne inflammation

BACKGROUND

Reactive oxygen species generated by neutrophils are closely correlated with the pathogenesis of a variety of inflammatory skin diseases. The aim of this study was to investigate the possible role of reactive oxygen species generated by neutrophils in the mediation of acne inflammation.

METHODS

Bacterial phagocytotic stimuli, mediated by opsonin activity, were applied to whole blood, and neutrophil hydrogen peroxide production was measured.

RESULTS

Patients with acne inflammation showed a significantly increased level of hydrogen peroxide produced by neutrophils compared to patients with acne comedones and healthy controls. There were no marked differences in the level of hydrogen peroxide produced by neutrophils between patients with acne comedones and healthy controls. In addition, patients with acne inflammation treated by oral administration of minocycline hydrochloride, a drug that inhibits hydrogen peroxide generation by neutrophils, showed a significant decrease in the ability of neutrophils to produce hydrogen peroxide in accordance with a decrease in the inflammatory activity of acne lesions.

CONCLUSIONS

The present study seems to suggest that acne inflammation is mediated in part by hydrogen peroxide generation by neutrophils.

Ocular surface inflammation induced by Propionibacterium acnes

PURPOSE

In the eye, is commonly isolated in the lid, conjunctiva, and meibomian gland secretion. Well known as a causative bacterium of granulomatous endophthalmitis and a potent inflammatory stimulus, reportedly induces a delayed-type hypersensitivity (DTH) response and forms granulomas in the liver and lung in animal models. In this study, we examined whether can induce a DTH response in the cornea.

METHODS

Six- to 8-week-old female Lewis rats were immunized with heat-killed suspension of and assessed as to DTH response via ear challenge at 2 weeks after immunization. At 3 weeks after immunization, suspension was injected in the rat corneal stroma, which was then observed biomicroscopically at 6, 24, and 48 hours after injection. Phenol-killed suspension was also used for the comparison. Histological examination was also performed on the corneal tissues, using hematoxylin and eosin staining as well as immunohistochemical staining against CD4 and CD8 T cells.

RESULTS

Rats immunized with suspension showed significantly higher ear swelling values at both the 24- and 48-hour measurements than did the naïve controls (p < 0.005). Massive cellular infiltration with stromal edema was observed biomicroscopically at 48 hours after injection of suspension in the corneal stroma. Histological study showed that the cell infiltration pattern was similar to that of DTH in the skin, i.e., neutrophils infiltrated at 6 hours, followed by mononuclear cells that, including macrophages and lymphocytes, increased and mixed with neutrophils, accompanied by stromal edema at 48 hours. Immunohistochemical study revealed that CD4 T-cell infiltration in the corneal stroma appeared to predominate over CD8 T-cell infiltration.

CONCLUSIONS

These results indicate that can induce a DTH response in the cornea and may be a causative bacterium of ocular surface inflammation.

Effect of palmitic acid on neutrophil functions in vitro

BACKGROUND

It has been shown that in acne comedones the proportion of linoleic acid is markedly decreased, while palmitic acid is significantly increased. We previously reported that the decreased proportion of linoleic acid, which markedly suppresses neutrophil reactive oxygen species (ROS) generation and phagocytosis, contribute to the worsening of acne inflammation. The aim of this study was to examine the effect of palmitic acid on neutrophil functions in vitro.

METHODS

We investigated the effect of palmitic acid on inflammatory parameters such as neutrophil chemotaxis, phagocytosis, and ROS generation. Reactive oxygen species generation in a cell-free, xanthine-xanthine oxidase system was also assessed. The species examined were superoxide radical anion (O2-), hydrogen peroxide (H2O2), and hydroxyl radical (OH.).

RESULTS

Palmitic acid significantly decreased H2O2 generation both by neutrophils and in the xanthine-xanthine oxidase system, while neutrophil chemotaxis and phagocytosis as well as O2- and OH. generation by both systems were not markedly affected in the presence of palmitic acid.

CONCLUSIONS

The present study suggests that palmitic acid may be involved in the pathogenesis of acne inflammation from a standpoint of oxidative tissue injury.

The evolving role of Propionibacterium acnes in acne

Propionibacterium acnes is a member of the resident cutaneous flora. Sebaceous follicles involved in acne are characterized by the accumulation of abnormally desquamated corneocytes and excess sebum-the microcomedo. This environment provides ideal growth conditions for P acnes. Several orders of magnitude level of P acnes are found in microcomedos. P acnes produces a variety of chemotactic factors and proinflammatory molecules that are responsible for the inflammatory phase of acne. Antibiotic therapy works by reducing the viable number of P acnes as well as by reducing the production of inflammatory stimuli. Antibiotic therapy has been a mainstay of treatment for more than 30 years. In the last decade, decreased sensitivity to antibiotics has developed and clinical resistance has been described. This development threatens the usefulness of antibiotic therapy in the future.

Post-acne scarring: a short review of its pathophysiology

The onset of acne is an expected phenomenon in adolescence. However, its arrival produces long-term psychological and physical sequelae for the individual. A review of available data illustrates the pathophysiological sequence of the advent of post-acne scarring from its humble beginnings as a microscopic comedone to its eventual devastating end point of indented or exophytic scars. Acne scarring shows many different forms and is explainable by the depth and severity of the antecedent inflammation and the ability of the individual to heal these lesions. Post-acne scarring is debilitating and socially disabling for many and is the avoidable outcome of untreated or inadequately treated acne. Treatment will depend on the resultant scar topography.

Acne vulgaris: yesterday, today and tomorrow

Acne vulgaris is one of the commonest diseases known to humanity, affecting up to 98% of all adolescents. This review examines important aspects of its epidemiology, aetiology and management in Australia in the year 2000, in comparison with a symposium in the inaugural volume of the Australian Journal of Dermatology in 1951.

Role of hormones in pilosebaceous unit development

Androgens are required for sexual hair and sebaceous gland development. However, pilosebaceous unit (PSU) growth and differentiation require the interaction of androgen with numerous other biological factors. The pattern of PSU responsiveness to androgen is determined in the embryo. Hair follicle growth involves close reciprocal epithelial-stromal interactions that recapitulate ontogeny; these interactions are necessary for optimal hair growth in culture. Peroxisome proliferator-activated receptors (PPARs) and retinoids have recently been found to specifically affect sebaceous cell growth and differentiation. Many other hormones such as GH, insulin-like growth factors, insulin, glucocorticoids, estrogen, and thyroid hormone play important roles in PSU growth and development. The biological and endocrinological basis of PSU development and the hormonal treatment of the PSU disorders hirsutism, acne vulgaris, and pattern alopecia are reviewed. Improved understanding of the multiplicity of factors involved in normal PSU growth and differentiation will be necessary to provide optimal treatment approaches for these disorders.

Managing acne in adolescents

Acne is the most common skin disorder affecting adolescents. Although no cure exists for acne, most patients benefit from currently available medications, and most can be managed effectively by their primary care providers. By offering this care, pediatricians can reduce the emotional burden of acne and help to prevent the permanent scarring so commonly seen in the past.

Treating acne. A practical guide

Acne is the most common skin disorder affecting adolescents. Although there is no cure for acne, most patients benefit from currently available medications, and most can be managed effectively by the primary care provider. By offering this care, the clinician can reduce the emotional burden of acne and help prevent the permanent scarring commonly seen in the past.

Acne: a review of immunologic and microbiologic factors

Acne vulgaris is a self-limiting skin disorder seen primarily in adolescents, whose aetiology appears to be multifactorial. The four main aetiological factors are hypercornification of the pilosebaceous duct, increased sebum production, colonization with Propionibacterium acnes, and subsequently the production of inflammation. Considerable investigation has addressed the immunologic reaction to extracellular products produced by the acne-causing organism, P acnes. The immunologic response involves both humoral and cell-mediated pathways. Further research should clarify the role of complement, cytotoxins, and neutrophils in this acne-forming response.

Immunohistochemical investigation of evolving inflammation in lesions of acne vulgaris

The mechanisms involved in the development of inflammation in acne vulgaris have yet to be elucidated. Previous studies have shown that the initial cellular infiltrate in early inflammatory lesions is mononuclear, predominantly CD4 positive T cells. The aims of this study were to investigate the pattern of expression of adhesion molecules and HLA-DR in evolving acne lesions. Forty-nine patients with moderate to severe acne were biopsied following lesion mapping. Lesions were classified according to their duration of inflammation as up to 6 h, from 6 to 24 h, from 24 to 48 h and from 48 to 72 h. The cellular infiltrate was determined using monoclonal antibodies to CDI, CD3, CD4 and CD8. The expression of ICAM-1, E-selectin. VCAM-1 and HLA-DR was determined. Early (6 h) lesions had perivascular CD3 positive T-cell infiltrates which were predominantly CD4 positive. This was associated with vascular expression of ICAM-1, E-selectin, VCAM-1 and HLA-DR. Periductal infiltrates were present in 70% of the early lesions (up to 6 h). The cells were predominantly CD4 positive and associated with a high level of HLA-DR and ICAM-1 expression. Periductal infiltration increased with time and persisted to 72 h. ICAM-1 and HLA-DR were expressed epidermally in early and late lesions. CD1 positive cells were a minor, but consistent element in the perivascular and periductal infiltrates of early and late lesions. There was no statistically significant difference in the levels of expression of E-selectin, VCAM-1, ICAM-1 or HLA-DR for lesions of different duration. The pattern of HLA-DR and adhesion molecule expression plus the nature of the cellular infiltrate supports the hypothesis that inflammation in acne is mediated by CD4 positive T cells.

Inflammation in acne vulgaris

Recent findings suggest that an overly vigorous immune response to Propionibacterium acnes may be the fundamental problem in patients with inflammatory acne. These data and evidence for the antiinflammatory effects of acne medications are reviewed.

Infection caused by Propionibacterium in children

Three hundred eighty-six isolates of Propionibacterium sp. were recovered from 2,003 specimens studied for the identification of anaerobic bacteria in children during a 15-year period. Three hundred forty-three (89%) of these were Propionibacterium acnes. A total of 50 (13%) Propionibacterium isolates identified from 45 patients were considered to cause infection. Clinically significant infections caused by Propionibacterium sp. were associated with bacteremia in 10 children; ear infection in eight; abscesses in seven; adenitis and central nervous system infection in five each; burns in four; wounds in three; tumors and bone in two each; and cysts, eye, sinus, and mastoid in one each. Predisposing or underlying conditions were present in 33 children (73%). These included the presence of a foreign body (17), immunodeficiency (six), malignancy (five), diabetes (five), previous surgery (four), and steroid therapy (two). Antimicrobial therapy was given to 41 (91%) children. Surgical drainage was concomitantly performed in 22 (49%). Four patients died. This study highlights the importance of Propionibacterium sp. as an unusual, but potentially important, pathogen in children.

Acne fulminans and 13-cis-retinoic acid

We report a case of acne fulminans occurring during treatment with 13-cis-retinoic acid for cystic acne. Continuing the treatment with 13-cis-retinoic acid without systemic steroid eventually cleared the systemic manifestations and skin lesions. We review the literature and discuss its pathogenesis.

Pro-inflammatory levels of interleukin-1 alpha-like bioactivity are present in the majority of open comedones in acne vulgaris

The factors that initiate the inflammatory response in acne are not known. The presence of pro-inflammatory cytokines in acne comedones was therefore investigated. One hundred eight open comedones were collected from 18 untreated acne patients (10 male, 8 female). Each comedone was homogenized and centrifuged, and the supernatant was analyzed for bioactive and immunochemically detectable IL-1 alpha, IL-1 beta, and TNF alpha. Viable counts of propionibacteria, staphylococci, and Malassezia spp. were determined in the comedone pellet. Bioactive IL-1 alpha-like material was demonstrated in 76% of open comedones (range of 23-4765 pg IL-1 alpha-like bioactivity/mg of comedone material). In 58% of comedones, levels exceeded 100 pg/mg. There was no correlation between IL-1 alpha-like bioactivity and IL-1 alpha determined immunochemically. Bioactive IL-1 beta was not detected in any comedones. Twenty-four percent contained low levels of immunochemical IL-1 beta (range 12-103 pg IL-1 beta/mg comedone material). Bioactive TNF alpha was detected in three comedones with a further five comedones containing immunochemical TNF alpha (range of 61-820 pg TNF alpha/mg comedone material). The majority of open comedones (97%) contained microorganisms. There was, however, no significant correlation (Spearman's rank) between levels of any cytokine, in particular IL-1 alpha-like bioactivity, and numbers of microorganisms. Thus, bioactive IL-1 alpha-like material in the majority of open comedones may be concerned in the initiation of inflammation in acne following spongiosis or rupture of the pilosebaceous follicle wall.

Acne vulgaris. Pathogenesis and treatment

Acne vulgaris is a multifactorial disease involving abnormalities in follicular keratinization, sebum production, proliferation of Propionibacterium acnes, and inflammation. Treatment is directed toward reversing these underlying pathogenic factors. Therapeutic options include topical comedolytics, topical and systemic antibiotics, hormonal manipulations, and oral retinoids.

Effects of subminimal inhibitory concentrations of erythromycin, tetracycline, clindamycin, and minocycline on the neutrophil chemotactic factor production in Propionibacterium acnes biotypes 1-5

Biotypes 1-5 Propionibacterium acnes (P. acnes) strains were grown in the presence of 1/10 minimal inhibitory concentrations (sub-MIC) of erythromycin (EM), tetracycline (TC), clindamycin (CLDM), or minocycline (MINO) and their culture filtrates were assayed for human neutrophil chemotactic activity using Boyden chamber methods. The addition of sub-MIC of MINO to the medium strongly suppressed the neutrophil chemotactic activity of the culture filtrates of P. acnes strains of all biotypes. In contrast, with sub-MIC of EM, TC, or CLDM, the activity of the culture filtrates of P. acnes strains of biotypes 2 and 3 were suppressed but those of biotypes 1, 2, and 5 were not. These results indicate that sub-MIC of MINO is capable of decreasing the inflammatory capacity of P. acnes strains of all biotypes.

Suppressive effects of linoleic acid on neutrophil oxygen metabolism and phagocytosis

On the basis of recent reports that the proportion of linoleic acid (C18:2Cis 9,12), a free fatty acid, is markedly decreased in acne comedones and that tetracycline is effective against acne comedones by acting directly as an antioxidant on infiltrating neutrophils, we investigated the effect of linoleic acid on several inflammatory parameters of neutrophils, including neutrophil chemotaxis, phagocytosis, and generation of reactive oxygen species (ROS). Linoleic acid significantly decreased phagocytosis and the generation of O2-, H2O2, and OH.by neutrophils, whereas it did not significantly inhibit neutrophil chemotaxis or decrease the ROS levels generated in a cell-free, xanthine-xanthine oxidase system. The present study seems to suggest that decreased levels of linoleic acid in acne comedones contribute, in part, to the worsening of acne inflammation by the failure of low levels of linoleic acid to suppress neutrophil phagocytosis and ROS generation.

Microbiology of the skin: resident flora, ecology, infection

Humans exist in an environment replete with microorganisms, but only a few become resident on the skin surface. The skin possesses protective mechanisms to limit colonization, and the survival of organisms on the surface lies in part in the ability of the organisms to resist these mechanisms. Microbial colonization on the skin adds to the skin's defense against potentially pathogenic organisms. Although microbes normally live in synergy with their hosts, occasionally colonization can result in clinical infection. Common infections consist of superficial infections of the stratum corneum or appendageal structures that can respond dramatically to therapy but commonly relapse. In rare circumstances, these infections can be quite severe, particularly in immunocompromised patients or in hospitalized patients with indwelling foreign devices. These infections are often resistant to conventional antibiotics and can result in infection with other opportunistic pathogens.

Analysis of the proinflammatory property of epidermal cyst contents: chemotactic C5a anaphylatoxin generation

We investigated in vitro the contents of epidermal cysts for complement activation and found that they activated complement mainly through the alternative pathway. Chemotactic C5a anaphylatoxin produced by the cyst contents after contact with serum most likely plays a significant role in the initiation and aggravation of inflammation in ruptured epidermal cysts. Our additional study disclosed that components of three representative follicular resident microorganisms (Pityrosporum ovale, Propionibacterium acnes, and Staphylococcus epidermidis) also produced C5a anaphylatoxin mainly through the alternative pathway; the C5a production was more vigorous than that by a virulent pathogen, Staphylococcus aureus. These results suggest that accidental colonization of the cyst contents by these follicular microbial flora further augments the inflammatory changes in ruptured epidermal cysts.

Leukocyte chemotactic properties of soluble horny contents in epidermal cysts

Epidermal cysts are one of the most common tumors of the skin. Although asymptomatic ordinarily, they may sometimes become severely inflamed with massive invasion of polymorphonuclear leukocytes (PMN). We studied in vitro PMN chemotactic properties of the aqueous extract prepared from the horny material of epidermal cysts obtained from three patients. A crude aqueous extract of the horny content of the cysts showed PMN chemotactic activity, which, however, was less than that of a horny layer extract prepared from normal skin. Characterization of PMN chemotactic activity using a Sephadex G-75 column showed a peak in the low molecular weight fractions eluting between the vitamin B12 and phenol red markers, which corresponds with the peak of absorbance at 280 nm. The chemotactic substances withstood boiling and trypsin or protease digestion. Although the chemotactic activity was partially ether-extractable, the presence of leukotriene B4 was not demonstrated by radioimmunoassay. In addition to their own chemotactic activity, the horny extracts of epidermal cysts showed cytotaxigenic properties in the presence of fresh serum.

Isotretinoin produces significant inhibition of monocyte and neutrophil chemotaxis in vivo in patients with cystic acne

The effect of oral isotretinoin (13-cis-retinoic acid) on in vivo chemotactic responses was studied longitudinally in 7 patients with cystic acne. As measured in a microchamber chemotaxis assay, both monocyte and neutrophil chemotaxis were inhibited 98% (p less than 0.001) during isotretinoin treatment. In vivo chemotactic responses returned to normal within 2 months of cessation of treatment. Biopsies of skin chamber sites from patients on isotretinoin showed no significant dermal or epidermal leukocytic accumulation in response to autologous zymosan-activated serum, whereas chambers from controls showed extensive neutrophilic infiltrates even in the epidermis. In contrast, in vitro chemotactic responses of neutrophils and monocytes from patients on isotretinoin were not diminished. Sera and plasma from patients on isotretinoin contained no inhibitors of chemotaxis, and activated sera from these patients were excellent attractants for normal monocytes. We postulate that isotretinoin produces significant anti-inflammatory effects by inhibition of monocyte and neutrophil chemotaxis across intact biologic barriers in vivo.

Erythromycin 2% gel in comparison with clindamycin phosphate 1% solution in acne vulgaris

One hundred two patients with mild to moderate facial acne vulgaris completed a 12-week, investigator-masked, randomized, parallel-group comparison of a gel formation of erythromycin (2%) with clindamycin phosphate 1% solution. Patients were evaluated at a baseline visit and after 4, 8, and 12 weeks of twice-daily treatment. Both medications significantly reduced the numbers of papules and open and closed comedones. No significant differences in lesion count reductions were detected between the treatment groups after 8 and 12 weeks of treatment. By the end of 12 weeks, 48% of the patients in the erythromycin group and 47% in the clindamycin group had good or excellent responses to treatment. No patient was terminated from the study for side effects. Most patients, 65% in the erythromycin 2% gel group and 67% in the clindamycin phosphate 1% solution group, had a favorable impression of the overall cosmetic characteristics of their study medication.

Rational therapy for acne vulgaris: an update on topical treatment

Acne vulgaris is a disorder of sebaceous follicles that usually begins at the time of the sharp increase in androgen production that occurs in adolescence. This disease is most prevalent among teenagers, but it does occur in patients in their twenties and thirties. Three major areas of pathophysiology have been identified in acne: hyperkeratinization and obstruction of sebaceous follicles, resulting from abnormal desquamation of follicular epithelium; an androgen-stimulated increase in the production of sebum; and proliferation of Propionibacterium acnes, which generates inflammation. Disruption of the preclinical precursor lesion known as the microcomedo produces inflammation, which leads to the pustules and papules of clinical disease and may eventually result in scarring. Rational therapy for acne should be directed at the three factors involved in the pathophysiology of the disease. Tretinoin (all-trans-retinoic acid) acts to normalize desquamation of follicular epithelium, promote drainage of comedones, and inhibit formation of new ones. Salicylic acid is also comedolytic, but to a much lesser degree. Benzoyl peroxide and topical or systemic antibiotics work by decreasing the follicular population of P. acnes, thus reducing inflammation. Direct injection of corticosteroids may be used to reduce large inflammatory lesions. Physical removal of comedones is also useful. Severe nodulocystic acne and other cases that fail to respond to these measures may be treated systemically with isotretinoin (13-cis-retinoic acid).

Effect of antibiotics on the generation of reactive oxygen species

The relative antioxidant efficacy, in vitro, of several antibiotics was examined by studying their effects on the generation of reactive oxygen species (ROS) using zymosan-stimulated polymorphonuclear leukocytes (PMNL) and the cell-free, xanthine-xanthine oxidase system. The species investigated are superoxide radical anion (O2-.), hydrogen peroxide (H2O2), and hydroxyl radical (OH.). Three tetracyclines (tetracycline HCl, oxytetracycline HCl, and minocycline HCl), erythromycin, cephalexin, penicillin G, chloramphenicol, and streptomycin were used as test drugs. At concentrations comparable to therapeutic blood levels, tetracycline HCl, oxytetracycline HCl, minocycline HCl, and erythromycin inhibited some of the ROS production by PMNL. In the xanthine-xanthine oxidase system, only minocycline HCl suppressed the H2O2 level. Cephalexin, penicillin G, chloramphenicol, and streptomycin did not affect any of the ROS examined at the concentrations tested. The capacity of some of these agents to inhibit ROS generation by PMNL may account, in part, for their efficacy in inflammatory skin diseases such as acne vulgaris. The antioxidant effect of these antibiotics does not stem from their capability to scavenge ROS, but originates rather from their effect on PMNL cell function directly with resultant anti-inflammatory effects on the inflammatory processes.