Eczema Flashcards
Eczema
Skin inflammation that results from an allergy, and occurs when the immune system attacks itself, also known as a hypersensitivity reaction.
Atopic
A group of conditions caused by a decreased activity of the allergy immune system
How is eczema triggered?
Starts off with the environment, like an allergen, acting as a trigger. It is able to travel through the slightly porous skin, which is then picked up by an immune cell (antigen presenting cell). It presents the allergen to a t-helper cell, activating it into a TH2 cell.
What does the activation of TH2 cells stimulate?
They stimulate nearby B cells to produce immunoglobulin E antibodies specific to the allergen. They bind to the surface of other immune cells called mast cells and basophills.
T-Helper cells
Secrete cytokines which communicate with other cells of the immune system and activate them to eliminate pathogens by appropriate immune response.
Cytokines
Cell signalling molecules that aid cell to cell communication
B Cell
Type of white blood cell that bind to specific antigens and will initiate an antibody response. They produce immunoglobulin
What happens during second exposure to the allergen?
The allergen can cross link the immunoglobulin E antibodies, causing the release of pro-inflammatory molecules. The combined effect causes the blood vessels to dilate, attracting more immune cells to the area, creating inflammation.
Itch-scratch cycle
The outer layer of skin is weaker and more susceptible to inflammation. The damage done by scratching contributes to the breakdown of skin cells in the body, making it easier for foreign substances to get in. The inflammation makes the skin more leaky, allowing water to escape leaving the skin dry and scaly
Genetic causes of eczema
Alternations in filaggrin
Alterations in filaggrin
Eczema may be associated with a genetic lack of filaggrin, a protein that binds to keratin fibres in epithelial cells. Keratin gives the epidermis its protective properties. Filaggrin deficiency leads to a leaky skin barrier.
Symptoms of eczema
Dry skin, itching, discoloured patches, small raised bumps, sensitive raw skin, thickened scaly skin
What makes eczema worse?
Mould, dust mites, changes in the weather, stress and cigarette smoke
Atopic triad
Asthma, eczema and allergic rhinitis
How does filaggrin impact dry skin?
Filaggrin is converted into the skin’s natural moisturising factor, so a lack of it would cause dry skin.
Treatments
Emollients, topical corticosteroids, antihistamines, calcineurin inhibitors,
wet dressing and antibiotics
Emollients
Moisturisers used every day to stop the skin becoming dry. They cover the skin with a protective film to trap in moisture.
Topical corticosteroids
Creams and ointments used to reduce swelling and redness. They make blood vessels near the surface of the skin tighter, helping to decrease redness.
Antihistamines
To reduce itching by blocking the chemical histamine from affecting the cells. Histamine is released when the body detects something harmful.
Calcineurin inhibitors
Medicines which inhibit the enzyme that activates T-Cells of the immune system
Wet dressing
Involves wrapping the affected area with topical corticosteroids and wet bandages
Other methods for treating eczema
Identify and avoid triggers, dress in soft fabrics, manage stress, keep fingernails short.
Antibiotics
To treat infection if required.
Why does eczema cause itching?
Free nerve fibres are stimulated by nerve endings called C fibres in the epidermis. Nerve pathways are activated and messages travel to the brain
Why does eczema cause discoloured pathches?
Pigmentation is controlled by melanin; trauma to the skin can cause a loss of pigmentation in the affected area
Why does eczema cause bumps?
Bumps appear when the pores of the skin become clogged with dead skin cells, oil and bacteria
