Acne and Rosacea Charity Training Manual

Inflammation
The inflammatory response in acne is very specific. The initial inflammatory response leads to recruitment of neutrophils within the follicle which leads to pus
formation.
Studies, as discussed in section 3, have shown that T cells in early acne lesions are reactive to P acnes. A typical type 4 immunological response would lead to an
eczematous reaction if on the surface of the skin or an itchy papule if deep in the skin, so the response in acne must lead to a specific cascade which induces the
infiltration of neutrophils, possibly due to local production of cytokines.
Stimulation of Toll-like receptors by P acnes could result in a pustular reaction but the unanswered question is why do people with acne respond in this way
while people without acne who are still exposed to the bacterium do not?
A number of early studies suggested that the breakdown of sebum into free fatty acids by P acnes could trigger an inflammatory response. But studies in which
free fatty acids are injected into the skin have failed to demonstrate an inflammatory response.
Morphological studies have shown rupture of follicles which would allow highly inflammatory constituents of the follicle to escape into the dermis where they
could induce an acute inflammatory response.
Summary
Simplistically, in the acne sufferer, sebum production is abnormally high. Follicular hyperkeratosis restricts oil flow onto the surface of the skin with oil retained in
the follicle which solidifies. This is the cheesy material that you squeeze out when you squeeze blackheads. Follicular occlusion leads to pooling of oil in the
follicle which stimulates proliferation of P acnes and this leads to an inflammatory response with ultimate pus formation. The pus takes the path of least
resistance and in most will point to the surface and bust onto the surface of the skin. If the inflammation is deeper in the follicle it may be retained within the
follicle and slowly resolve leading to clinical nodules, or may rupture into the dermis with damage to collagen and eventual scarring. Cystic lesion result from
fusion of adjacent inflamed follicles leading to lakes of pus with multiple heads.
Glossary
• Neutrophils – also known as polymorphs are white blood cells that will be induced to migrate into areas of inflammation or infection and lead to pus formation
• Type 4 response – immunological reactions have been classified into 4 types – type 4 is where the immune system reacts to a local antigen with a response of T
lymphocytes which leads to an eczema if it is on the surface of the skin or an itchy lump in the skin if it is deep in the skin.