Tag Archives: acne pathogenesis

Pathogenesis of Acne or How Does Acne Develop?

How Acne Occurs
How Does Acne Occur?

The pathogenesis of acne or how acne forms  includes a combination of factors affecting the integrity of the hair follicle and its oil producing gland, the sebaceous gland.

The study of how acne develops is a fascinating one. There are many points to be clarified regarding the pathogenesis of acne. What is the basic cause of acne? Why does it appear only on some parts of the body? Why does acne have a course with waxing and waning? What is the role of hormones, skin oiliness and germs in the development of acne?

There are four major causes contributing to acne development –

  1. Increased sebum production
  2. Colonization of the hair follicle duct with the germ Propionibacterium acnes
  3. Thickening and plugging of the hair follicle walls and opening, resulting in comedo formation
  4. Inflammation of the pilosebaceous unit. Pilosebaceous unit includes the hair follicle and its associated sebaceous gland.
How Acne Develops
Stages of Acne Development

How Acne Develops: Increased Sebum Production or Seborrhea

Sebum is the oily secretion from the sebaceous gland lying alongside the hair follicle. Sebum is responsible for maintaining the oiliness of the skin and the hair. It keeps the skin supple and smooth. In infancy and childhood, the sebaceous glands are small and inactive. The sebaceous glands enlarge and become active during puberty under the influence of the androgen hormones secreted by the adrenal and gonadal glands.

The increased production of sebum, seborrhea, may be genetically programmed; some individuals are more acne prone than others. It is also seen that sebum secretion and sensitivity of the sebaceous glands to the action of androgens vary from follicle to follicle and area to area. This is the reason why acne severity varies between different follicles and hair bearing areas of the body.

How Acne Develops: Bacteria Colonization

 The increased sebum secretion predisposes to the overgrowth of the bacteria Propionibacterium acnes within the hair follicle and the sebaceous gland. The action of these bacteria on the sebum is thought to produce irritant products like free fatty acids within the hair follicle. These and other chemical mediators known as cytokines are thought to be responsible for the thickening of the hair follicle, plug formation and inflammatory events in acne.

How Acne Develops: Comedogenesis or Comedo Formation

 The thickening of the hair follicle walls, known as ductal hypercornification, and the keratinous plug formation is the cause for the formation of the comedo, better known as the acne whiteheads and blackheads. Comedo formation is the first stage of development of acne. When the follicular opening is closed with the keratinous plug, it is known as closed comedone or whitehead, and when it is dilated, the open comedone or blackhead. The black color seen in the blackhead is not dirt, but due to the sebum changing color when it comes in contact with the atmospheric oxygen.

How Acne Develops: Inflammation

 Inflammation of the hair follicle and the sebaceous glands and the surrounding dermis is the final event in the moderate to severe types of acne. Inflammation results in red, painful and pus filled bumps in acne. Acne gets inflamed by a combined action of P.acnes, the bye products of the action of the bacteria on the sebum, the corneocytes lining the hair follicle duct and the inflammatory mediators induced by the sebaceous glands.  

The inflammation weakens the follicular and sebaceous gland walls which rupture to discharge the sebum and part of the comedone into the dermis. This induces a severe foreign body inflammatory reaction resulting in formation of acne cysts and nodules.

Recent Advances in Acne Pathogenesis Information

 The 2009 acne update from the Global Alliance to Improve Outcomes in Acne throws some interesting insights to the pathogenesis of acne:

The inflammatory events in acne precede the hyperkeratinization (thickening of the follicular walls).

  1. acnes specifically activate special receptors on the cell membranes of inflammatory cells.

The sebaceous gland is a neuroendocrine-inflammatory organ that coordinates and executes a local response to a variety of neuro-endocrinological and stress induced stimuli.

Sebaceous gland plays an important role in hormonally induced aging of skin.

In addition to their action on sebaceous gland activity, androgens have influence on the follicular cells (corneocytes) also.

Oxidized lipids in sebum (possibly altered by P.acnes) induce the production of inflammatory mediators.

Sebum contains several matrix metalloproteinases (MMPs) which play important roles in the inflammatory process of acne. The levels of MMPs are significantly reduced in the acne lesions following treatment.

The acne information provided above is a short review of how acne develops. The degree of plugging of the comedones and the extent of inflammation decides the severity of the pimples. Different types of acne are categorized according to the severity of the acne lesions.

Reference

  1. Simpson NB & Cunliffe WJ. Disorders of the Sebaceous Glands in Rook’s Textbook of Dermatology. 2004; 7: 43.1-43.75.
  2. Diane T, Gollnick H et al. New insights into the management of acne: An update from the Global Alliance to Improve Outcomes in Acne Group. J Am Acad Dermatol, 2009;60:S1-50.

    Published by Dr Hanish Babu, MD on 24th May, 2018

    Disclaimer
    The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or the website will not be responsible for any consequences. The images provided are for illustration purpose only and are copyrighted.

    Copyright 2018 © Dr Hanish Babu, MD

What is Acne?

What is Acne?

Acne, or pimples, is the commonest skin disease affecting almost 85% of teens at least once in their lifetime. It is a disease of the hair unit of the skin involving the oil producing sebaceous glands situated beside the hair. The sebaceous glands discharge their oily secretions into the hair canal.

Grade 3 or Papulopustular Acne
Moderate Acne: Grade 3 or Papulopustular Acne

Androgen hormones act on the sebaceous glands at puberty and increase their size and sebum (oil) production. The normal function of sebum is to keep the skin smooth and supple by providing an oily environment. Increased sebum secretion and the action of certain bacteria inside the hair canal results in acne formation.

The following series of articles will discuss about different types of acne and modalities of treatment of acne and its complications.

The links will become active as new articles are being added. Please visit this page regularly.

All About Acne

  1. Acne 101: The Acne Basics
  2. Causes of Acne
  3. Pathogenesis of Acne or How Does Acne Develop?
  4. Acne Triggers
  5. Who is at Risk of Developing Acne?
  6. What are the Different Types of Acne?
  7. Acne: Best Treatment Practices: Why Acne Should be Treated
  8. Acne: General Advices from Dermatologist
  9. Mild Acne: Frequently Asked Questions
  10. How to Treat Mild Acne
  11. Moderate Acne: Frequently Asked Questions
  12. How to Treat Moderate Acne
  13. Severe Acne: Frequently Asked Questions
  14. How to Treat Severe Acne
  15. FAQ on Very Severe Nodulocystic Acne
  16. How to Treat Very Severe Nodulocystic  Acne
  17. Does Food Affect Acne?
  18. Acne: Diet Recommendations
  19. Acne in Teens
  20. Acne in Adults: What it is and how to treat.
  21. Body Acne
  22. Acne Butt
  23. Skin Types
  24. Acne Mimics
  25. Acne: Frequently Asked Questions
  26. Topical Treatment for Acne
  27. Complications of Acne
  28. Acne Scar : Causes
  29. Acne Scar: Treatment
  30. Acne Scar: FAQ
  31. Acne Scar Solution
  32. Stress and Acne: Is it Real?
  33. Acne: Home Remedies: Are they Useful or Just Grandma’s Tales?
  34. Acne: Alternative Treatments: Are they Effective?
  35. Acne Myths
  36. Acne Products
  37. Acne during Pregnancy
  38. Skincare during Acne
  39. Chronic Acne: How to Deal with it
  40. Acne and Depression
  41. Acne Glossary
  42. Acne: Disclaimer

Published by Dr Hanish Babu, MD on 23rd May, 2018

Disclaimer

The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or the website will not be responsible for any consequences. The images provided are for illustration purpose only and are copyrighted.