Unit
- Sebaceous follicle physiology: Healthy sebaceous glands produce sebum that flows freely through follicle openings. In acne-prone skin, increased sebum production combines with abnormal follicular keratinization to create microcomedones, the precursor lesions. Androgen hormones, particularly dihydrotestosterone, stimulate sebocyte activity, leading to hyperseborrhea that overwhelms the follicle's ability to shed cells normally.
- Follicular hyperkeratinization: Retained desquamated corneocytes within the follicle form a keratin plug. This process is driven by increased levels of interleukin-1 alpha and decreased linoleic acid, which disrupt normal desquamation. The resulting microcomedone creates a hypoxic environment conducive to microbial proliferation.
- Cutibacterium acnes colonization: This anaerobic Gram-positive bacterium thrives in the lipid-rich, low-oxygen environment of blocked follicles. C. acnes activates toll-like receptors 2 and 4 on keratinocytes and sebocytes, triggering an inflammatory cascade that releases cytokines, chemokines, and matrix metalloproteinases.
- Inflammatory cascade initiation: The immune response to C. acnes and follicular rupture produces visible inflammation. Neutrophils infiltrate the follicle, releasing hydrolytic enzymes that damage the follicular wall. This process converts noninflammatory comedones into inflammatory papules, pustules, and nodules.
- Role of innate immunity: Keratinocytes and sebocytes produce antimicrobial peptides and inflammatory mediators. In acne, dysregulation of this innate immune response leads to chronic inflammation, even in early lesion development. This explains why anti-inflammatory therapies are effective even in non-inflammatory acne.
- Genetic predisposition factors: Family and twin studies show heritability estimates of 50-80% for acne susceptibility. Specific genetic variants affect sebum production, follicular keratinization, and inflammatory responses. Understanding these genetic factors helps predict treatment response and disease severity.
- Dietary influences on pathophysiology: High glycemic load diets increase insulin-like growth factor-1 (IGF-1) and insulin, which stimulate sebocyte lipogenesis and androgen production. Dairy consumption may also exacerbate acne through similar hormonal pathways. These metabolic effects directly modulate the pathophysiologic steps.
- Hormonal regulation in women: Estrogens reduce sebum production, while androgens increase it. Conditions like polycystic ovary syndrome (PCOS) cause prolonged anovulation, leading to unopposed androgen activity and increased acne severity. The menstrual cycle's luteal phase often triggers flare-ups due to progesterone-mediated changes.
- Role of neurogenic inflammation: Stress activates the hypothalamic-pituitary-adrenal axis, increasing corticotropin-releasing hormone (CRH) in sebocytes. CRH triggers sebum production and pro-inflammatory cytokine release. Additionally, substance P released from nerve endings around follicles promotes mast cell degranulation and leucocyte recruitment, worsening inflammatory lesions.
- Impact of skin microbiome dysbiosis: Beyond C. acnes, reduced microbial diversity on acne-prone skin correlates with lesion severity. Overgrowth of specific C. acnes phylotypes, combined with decreased populations of protective bacteria like Staphylococcus epidermidis, disrupts skin barrier function and amplifies inflammatory signaling through pattern recognition receptors.
Scope of Practice
Role: Acne Care Coordinator (Administrative)
Within scope:
- Educating patients on the pathophysiologic basis of acne using approved materials
- Documenting patient-reported triggers and family history during intake
- Coordinating referral pathways for patients with suspected hormonal disorders
Outside scope:
- Diagnosing acne subtypes or distinguishing from other skin conditions
- Prescribing or recommending specific treatments based on pathophysiology
- Interpreting laboratory tests related to hormonal or genetic factors
Quick Revision
- Acne pathogenesis involves four interrelated processes: hyperseborrhea, follicular hyperkeratinization, C. acnes colonization, and inflammation.
- Genetic and hormonal factors significantly influence disease expression and severity.
- Administrative staff can support education and documentation but must not diagnose or treat.