Recent Advances in Acne Pathogenesis

Implications for Therapy

Shinjita Das; Rachel V. Reynolds

Disclosures

Am J Clin Dermatol. 2014;15(6):479-488. 

In This Article

Abstract and Introduction

Abstract

Acne pathogenesis is a multifactorial process that occurs at the level of the pilosebaceous unit. While acne was previously perceived as an infectious disease, recent data have clarified it as an inflammatory process in which Propionibacterium acnes and innate immunity play critical roles in propagating abnormal hyperkeratinization and inflammation. Alterations in sebum composition, and increased sensitivity to androgens, also play roles in the inflammatory process. A stepwise approach to acne management utilizes topical agents for mild to moderate acne (topical retinoid as mainstay ± topical antibiotics) and escalation to oral agents for more resistant cases (oral antibiotics or hormonal agents in conjunction with a topical retinoid or oral isotretinoin alone for severe acne). Concerns over antibiotic resistance and the safety issues associated with isotretinoin have prompted further research into alternative medications and devices for the treatment of acne. Radiofrequency, laser, and light treatments have demonstrated modest improvement for inflammatory acne (with blue-light photodynamic therapy being the only US FDA-approved treatment). However, limitations in study design and patient follow-up render these modalities as adjuncts rather than standalone options. This review will update readers on the latest advancements in our understanding of acne pathogenesis and treatment, with emphasis on emerging treatment options that can help improve patient outcomes.

Introduction

Acne vulgaris is a chronic inflammatory skin disease that develops around the pilosebaceous apparatus and manifests as open and closed comedones as well as inflammatory papules, pustules, and nodules. Commonly involved sites are the face, chest, upper back, and upper arms. Inflammatory acne can result in potentially disfiguring scarring and post-inflammatory hyperpigmentation, highlighting the importance of treatment.

Acne pathogenesis begins with abnormal keratinization that causes impaction and distension of the lower portion of the infundibulum, forming the comedo.[1–3] Other factors include a complex interplay among sebum production, with changes in lipid composition, hypersensitivity to androgen stimulation, Propionibacterium acnes, and local inflammatory cytokines elaborated by the innate immune system.[4–10]

The general principles of acne treatment involve targeting the various pathogenic factors. The therapeutic ladder ranges from topical therapies for mild to moderate acne (retinoids and antimicrobials) to oral agents for moderate to severe acne (antibiotics, hormonal agents, and isotretinoin; of note, all oral treatments [except isotretinoin] should be prescribed in conjunction with topical treatment). More recently, physical modalities, such as radiofrequency, photodynamic therapy (PDT), and laser therapies have been studied.

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