Acta Demato-Venereologica 98-2CompleteContent | Page 22

262 INVESTIGATIVE REPORT Decrease in Diversity of Propionibacterium acnes Phylotypes in Patients with Severe Acne on the Back Marie-Ange DAGNELIE 1 , Stéphane CORVEC 1,3 , Mélanie SAINT-JEAN 1,2 , Valérie BOURDÈS 5 , Jean-Michel NGUYEN 1,4 , Amir KHAMMARI 1,2 and Brigitte DRÉNO 1,2 1 CIC, Inserm U1232, 2 Department of Dermatology, 3 Bacteriology and Hygiene Unit, Biology Institute, 4 Biostatistic Department, PIMES, Saint- Jacques Hospital, Nantes University Hospital, Nantes, and 5 Evaluation Department – CUTIS – Galderma R&D, Biot, France Propionibacterium acnes, a major member of normal skin microbiota, is subdivided into 6 phylotypes: IA1, IA2, IB, IC, II and III. This study investigated P. acnes subgroups on the face and back in patients with se- vere acne and in healthy controls. In 71.4% of patients with severe acne, P. acnes phylotypes were identical on the face and back, whereas this was the case in only 45.5% of healthy controls. The healthy group car- ried phylotypes IA1 (39.1%) and II (43.4%), whereas the acne group carried a high predominance of IA1 (84.4%), especially on the back (95.6%). In addi- tion, the single-locus sequence typing (SLST) method revealed A1 to be the predominant type on the back of patients with acne, compared with a wide diversity in the healthy group. We report here that severity of acne on the back is associated with loss of diversity of P. acnes phylotype, with a major predominance of phylotype IA1. The change in balance of cutaneous P. acnes subgroups might be an inducing factor in the ac- tivation of P. acnes, which could trigger inflammation. Key words: acne, P. acnes phylotypes; clonal complexes; SLST- types. Accepted Nov 13, 2017; Epub ahead of print Nov 14, 2017 Acta Derm Venereol 2018; 98: 262–267. Corr: Brigitte Dréno, Department of Dermatology, Nantes University Hos- pital, 1 Place Alexis Ricordeau, FR-44035 Nantes Cedex 01, France. E- mail: [email protected] A cne is one of the most common skin diseases world- wide, affecting up to 85% of the population (1). At the pathophysiological level, 2 factors play a crucial role: the sebaceous gland and Propionibacterium acnes. P. ac- nes is a commensal anaerobic Gram-positive bacterium of the healthy skin. This bacterial genus has high specificity, from face to feet areas (2). This study showed a predo- minance of Propionibacterium genus on the face and back. This microorganism diversity on the human body also depends on several factors, such as host factors (e.g. age, sex, hair follicle density) and environmental factors (e.g. occupation, clothing choice, antibiotic use) (3, 4). P. acnes plays an important role in the maintenance of normal cutaneous microbiota, by inhibiting the deve- lopment of some pathogenic bacteria, such as Staphylo- coccus aureus and Streptococcus pyogenes. It produces propionic acid and, thus, can maintain acidic pH in the doi: 10.2340/00015555-2847 Acta Derm Venereol 2018; 98: 262–267 pilo-sebaceous follicles. In addition to acne, P. acnes has also been implicated in deep infections and orthopaedic ab- scesses (5–7), lung abscesses (8), prostate cancer (9), and sarcoidosis (10). Its development in deep infections may be related to the secretion of a biofilm that increases both its adherence to surfaces and antibiotic resistance (11). In the skin, P. acnes, as an anaerobic bacterium, is located more specifically in the pilo-sebaceous follic- les. A number of studies have shown that P. acnes can activate innate immunity, mainly via Toll-like receptors (TLRs) expressed by keratinocytes and monocytes (12, 13). P. acnes also stimulates the secretion of interleukins (IL)-12, IL-8, IL-1β and IL-17 cytokines by monocytes (14). Thus, it plays a crucial ro le in the development of inflammatory lesions in acne. P. acnes population strains are divided into 6 main phylotypes: IA1, IA2, IB, IC, II and III. Recent genomic studies have also highlighted the presence of subgroups among phylotypes, according to genome analysis called multi-locus sequence typing (MLST) (15) and single- locus sequence typing (SLST). These cluster differentia- tions are called clonal complexes (CCs). Some P. acnes phylotypes are associated with skin disease conditions, such as phylotype III and progressive macular hypome- lanosis (16). Moreover, different P. acnes phylotypes are known to induce distinct immune responses in the context of acne (12, 17). The aim of this study was to determine and compare the different P. acnes phylotypes, CCs and SLST types on the face and back of patients with severe acne of the back vs. a healthy population. MATERIALS AND METHODS Recruitment of healthy volunteers and patients At the first visit, patients with acne who fulfilled the inclusion criteria were selected. The inclusion criteria were: age (16–35 years), at least 2 nodules on the back, complying with wash-out periods for acne drugs including systemic antibiotics (1 month), oral retinoids (6 months) and topical treatments (2 weeks). Healthy volunteers were selected according to inclusion criteria, including the total absence of acne on the face and back, and the absence of other history or current dermatological pathologies. All patients provided signed informed consent and the study was approved by the health authorities (Agence Nationale de Sécurité du Médi- cament et des Produits de Santé (ANSM); number 151141B-42) and ethics committee (Comité de Protection des Personnes (CPP); number 21–15). This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2018 Acta Dermato-Venereologica.