Acne: Bad and good bacteria identified

A genomic approach to comparing acne-ridden skin with clear human skin has revealed a bacterial strain that may protect against the disease. The work was published online February 28 in the Journal of Investigative Dermatology by Sorel Fitz-Gibbon, PhD, from the Department of Molecular and Medical Pharmacology, Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, and colleagues.

Four of 5 people in the United States develop acne at some point. Although dermatologists no longer blame blemishes on too much chocolate or fatty foods, commonly prescribed acne drugs such as benzoyl peroxide, antibiotics, and isotretinoin (Accutane, Roche) have been used for decades, although they are not ideal. Antibiotics are usually ineffective in severe cases, and isotretinoin both has adverse effects and is teratogenic.

Propionibacterium acnes is a dominant skin commensal that colonizes pilosebaceous units, in which certain strains are hypothesized to stimulate development of acne vulgaris. The population sizes of the bacteria are similar among individuals, but the proportions of different strains vary between people prone to acne and people with clear skin. Similar to Staphylococcus aureus, only certain strains of the bacteria are pathogenic.

The researchers sequenced bacterial genomes to better define the genetic compositions of the P acne component of the skin microbiome in acne-marked vs healthy skin. The strategy revealed "a previously unreported portrait of the microbiota of pilosebaceous units at the bacterial strain level," the researchers write.

Dr. Fitz-Gibbon and colleagues applied over-the-counter pore-cleansing strips to the noses of 49 people with acne and 52 participants with clear skin, sampling P acnes in whiteheads or blackheads. The investigators typed bacterial strains according to 16S ribosomal DNA sequences (ribotypes), assigning each strain an acne index based on prevalence among patients with acne. This approach identified 11,009 ribotypes, but only a few were abundant in either patient group.

Genome sequencing was the next step. Team members from Washington University in St. Louis, Missouri, sequenced the genomes of 66 previously unreported P acnes strains from the samples and compared 71 bacterial genome types overall. Author Shuta Tomida, PhD, also from the Department of Molecular and Medical Pharmacology, Crump Institute for Molecular Imaging, David Geffen School of Medicine, identified DNA differences among the strains.

Beneficial Bacteria

Three genomically identified strains are of potential clinical significance. Two strains were discovered in 1 of 5 volunteers with acne, but rarely in clear-skinned people. Conversely, a third bacterial strain appeared to be common in healthy skin yet was rare in skin with acne, suggesting a protective role.

The findings may have practical applications, the authors write, such as the development of a probiotic topical preparation to favor the protective bacterial strain or drugs to selectively target acne-related bacteria. A simple skin test might predict whether a person has an increased risk of developing aggressive acne.

Further studies might address identifying host factors that contribute to acne and matching microbiome subtypes with clinical subtypes of acne, such as cystic, pustular, or inflammatory acne.

"By combining a metagenomic study of the skin microbiome and genome sequencing of this major skin commensal, this study provides insight into potential bacterial genetic determinants in acne pathogenesis and emphasizes the importance of strain-level analysis of the human microbiome to understand the role of commensals in health and disease," the researchers conclude.

Source: http://www.medscape.com/viewarticle/780020?nlid=28944_1301&src=wnl_edit_dail

Fats, sugar and processed foods linked to acne

Adolescents eating a diet high in fat, sugar, processed meat, and carbohydrates have a higher risk for developing acne than those who have healthier diets, suggest findings from a study on adolescents living in Central Anatolia, Turkey.

The study also showed that despite nearly two thirds of surveyed adolescents experiencing acne, only 11.5% consulted a doctor for the condition.

"As the most effective way of managing acne [recurrences] is to prevent its occurrence, it is of primary importance to receive medical help early," say AE Koku Aksu (Eskisehir Osmangazi University, Turkey) and co-researchers.

For the study, the researchers asked 2230 adolescents, aged on average 15.1 years, to complete a questionnaire about their acne and another about their daily dietary habits. Adolescents also had their acne evaluated by a doctor.

Doctors diagnosed that 60.7% of adolescents in the study were currently experiencing acne, with 21.0% presenting severe (grade 3 or 4) acne. In addition, 83.9% of adolescents reported ever having acne.

The researchers also found that, despite 25.0% of adolescents experiencing a worsening of their condition, only 11.5% went to visit their doctor.

Girls aged 13-14 years were more affected than boys of the same age, although between the ages of 15 and 18 years boys appeared to experience more acne than girls.

When the team assessed dietary risk factors for acne, they found that adolescents who consumed excess fat, sugar, processed meats (eg, sausages and burgers) and refined carbohydrates (eg, pastries and cakes) were 20-39% more likely to develop acne than those who had healthier diets.

Other risk factors associated with acne included being aged 15-18 years and being overweight, while face washing three or more times per day was associated with a 32% reduced risk for developing acne compared with face washing once a day.

"Increasing awareness is critical for convincing adolescents to seek medical help earlier," conclude the researchers in the Journal of the European Academy of Dermatology and Venereology.


Source: http://www.medwire-news.md/265/95866/Most_Popular_Stories/Excess_fat,_sugar,_processed_foods_linked_to_acne_development.html