Acne: a review of immunologic and microbiologic factors

Abstract

SummaryAcne 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 cellmediated pathways. Further research should clarify the role of complement, cytotoxins, and neutrophils in this acne-forming response. Keywords: acne vulgaris; Propionibacterium acnesAcne vulgaris, the most common cutaneous disorder, is manifested by comedones, papules, pustules, and cysts. The aetiology of acne appears to be multifactorial. The exact mechanism triggering the development of the comedone and the stimuli causing the non-inflamed lesion to become inflamed are poorly understood. The microbiology of acne vulgaris and its immunologic ramifications constitute the major thrust of present research in the elucidation of the pathogenesis of the inflammatory acne lesion.The microbiology of the pilosebaceous unit involves three coexisting groups of microorganisms: Gram-positive, coagulase-negative cocci (staphylococci and micrococci); anaerobic diphtheroids (Propionibacterium acnes and Propionibacterium granulosum); and lipophilic yeasts (Pityrosporum species). The microflora of comedones is qualitatively identical to that of the normal sebaceous follicle.The staphylococci and micrococci are aerobes; therefore, their site of growth within the sebaceous unit is superficial, and these organisms are unable to reside in the anaerobic conditions of the infra-infundibulum where the inflammatory reaction occurs in acne. Antibiotics that selectively eliminate these organisms do not aVect the clinical response of patients, 1 and their role in acne pathogenesis is negligible.The lipophilic yeasts that reside in hair follicles have been divided morphologically into Pityrosporum ovale and Pityrosporum orbiculare. These represent a complex of organisms and have been reclassified as Malassezia furfur as well as other Malassezia species.2 The filamentous forms that are usually associated with a pathologic condition are not seen in acne lesions and, save for tinea versicolor, these organisms appear not to play a significant aetiologic role in any disease state.If the microbial flora is significant in the pathogenesis of acne, the most likely organism to blame is P acnes, a strict anaerobe that has been shown serologically and biochemically to be identical to Corynebacterium parvum, a potent stimulator of the reticuloendothelial system. 3 This organism has been used as an immunostimulatory adjunct in chemotherapy of numerous tumours.3-6 P acnes is overwhelmingly the predominant microorganism in the normal pilosebaceous follicle, as well as in the acne state, and has been divided into two serotypes and fiv...

Efficacy and safety of intense pulsed light in the treatment of mild-to-moderate acne vulgaris

“…IPL is being used to treat acne vulgaris in different countries of Asia with promising results [12] .The pathogenesis of acne vulgaris involves follicular epidermal hyperproliferation with subsequent plugging of the follicle, excess sebum production, the presence and activity of the commensal bacteria P. acne, and inflammation [13] . The therapeutic effects of IPL are attributed mainly to photothermolysis of the sebaceous glands.…”

Antimicrobial effects of Indian medicinal plants against acne-inducing bacteria

“…It is implicated in the development of inflammatory acne by its capability to activate complements and by its ability to metabolize sebaceous triglycerides into fatty acids, which chemotactically attract neutrophils. On the contrary, Staphylococcus epidermidis, an aerobic organism, usually involves in superficial infections within the sebaceous unit 3 . These factors provide a potential target for treatment.…”

Use of Indonesian Medicinal Plants Products Against Acne

“…In addition, large numbers of P. acnes occur in all stages of the acne process (Zane, 2005). Antibacterial therapy in the treatment of acne suggests that microbial components play an important role in acne progression and reducing the population numbers of bacteria such as P. acnes, S epidermidis, and S. aureus is an appropriate parameter of the therapeutic effectiveness of an antibiotic (Burkhart et al, 1999) .…”

“…This bacterium plays a central role in the current understanding of acne pathogenesis (Zane, 2005), and is the target of oral and topical antibiotic usage. Indeed, reduction in P. acnes numbers is an effective parameter of the therapeutic effectiveness of antibiotic (Burkhart et al, 1999).…”