Eczema is a term for several different types of skin inflammation and is characterized by itching, redness, skin edema, dryness, crusting, flaking, blistering, cracking, oozing, or bleeding. Eczema is thought to be inherited, although its etiology is poorly understood. It is thought to be a more chronic type I hypersensitive reaction. Type 1 hypersensitive reactions manifest themselves differently in different tissues. Eczema occurs on skin.
Eczema involves the release of pro-inflammatory substances triggered by an allergy or hypersensitive reaction. This allergy reaction is caused by the degranulation of mast cells, eosinophils or basophils by IgE. One of the possible purposes of type 1 hypersensitive reaction is to provide protection against parasites. The itch caused by the degranulation of mast cells will cause scratching and this will be likely to remove the parasite.
Mast cells synthesize and store histamine, TNF α, and other inflammatory mediators in granules. Unlike other Immunoglobulins, the Fc portion of IgE bind tightly and irreversibly to the Fcεri receptor on the mast cells, basophils or eosinophils in the absence of antigen. The granules are released (degranulated) immediately when the IgE binds to an allergen (Allergen is a non dangerous enviromental antigen that induces a hypersensitive reaction). The histamine released will bind to the H1 receptor on endothelial cells of blood vessels. This triggers vasodilation and increase in vessel permeability, causing the entry of other effector cells into the allergy- containing tissue. TNF α released will activate endothelial cells causing them to increase expression of adhesion molecules. This promotes leukocyte traffic from the blood into the inflamed tissue. Thus, acute inflammation will occur. However, after the immediate reaction phase, there will be a late-phase reaction due to other inflammatory substances such as leuikotrienes that are synthesized by mast cells.
Scratching not only has a significant effect on the appearance of the involved skin but will also further damage the skin barrier and will provoke the release of pro-inflammatory mediators such as cytokines that make the itching worse. Scratching may well produce breaks in the skin which, which are also itchy and leads to a vicious itch-scratch cycle being set up which increases the risk of secondary infection which is most frequently caused by the bacteria Staphylococcus aureus. (Adapted from http://www.eczemaguide.com/eczema_basics/facts/itch.html)
One of the best ways to treat eczema is using a corticosteroid such as Betnovate-N cream. BNC contains betamethasone valerate that helps to reduce the redness, itching, and swelling of skin conditions. When betamethasone is applied to the skin it works by acting inside the skin cells to decrease the release of these inflammatory substances. BNC also contains neomycin sulphate, an antibiotic of the aminoglycoside type.. It works by entering bacterial cells and interfering with the production of proteins that the bacteria need to divide and multiply. This rapidly kills the bacteria. This medication is usually applied 2 or 3 times daily or according to doctor’s instruction. Enough medication should be applied to completely cover the affected area with a thin film. The user should avoid applying the medication in or near the eyes as glaucoma may occur. Caution should be taken when using BNC. Please consult your doctor or pharmacist!
References:
Peter Parham. 2005. The Immune System. Garland Science. USA.
Anon. Eczema. Year unknown. http://en.wikipedia.org/wiki/Eczema
Anon. Itch. Year unknown. Accessed online from http://www.eczemaguide.com/eczema_basics/facts/itch.html
Anon. Betnovate. Year Unknown. Accessed online from http://www.medbroadcast.com/drug_info_details.asp?brand_name_id=706
Anon. Betnovate-N cream/ointment. Year unknown. Accessed from http://www.tiscali.co.uk/lifestyle/healthfitness/health_advice/netdoctor/archive/100000295.html
