Chinese herbal medicine research in eczema treatment

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease commonly associated with allergy [1,2]. About 15% of children suffer from this disease [2-4]. Typical onset of the disease is occurs in the children under five years of age [2,5]. The condition improves in most patients before adulthood. Management of this condition includes use of emollient, topical and systemic antimicrobial agents, corticosteroid or immunomodulating agents [2]. Corticosteroids (CS) are the common treatment for AD in either topical or systemic form. CS has a wide range of immunomodulatory effects, such as the suppression of cytokine production, adhesion molecule expression and leukocyte chemotaxis [6]. CS is also associated with deranged metabolism, growth suppression and increased susceptibility to infections. In particular, the use of potent topical CS in AD may cause significant suppression of the hypothalamic-pituitary-adrenal axis [7]. More specific immunomodulatory agents (eg topical tacrolimus) are available [2,8]. As there is still no cure for AD, various dietary therapies including Chinese medicine are adopted by the patients, especially in Asia [9]. However, the beneficial effects of Chinese medicine on children with AD have not been consistently demonstrated [10]. A limited number of Chinese medicine trials in children and adults with AD did not show convincing results [11-14].Pathogenesis of AD involves complex interactions between susceptible genes (filaggrin genes), immunological factors (immunoglobulin E, eosinophils, T helper cells, chemokines), skin barrier defects, infections, neuroendocrine factors (brain derived neurotrophic factor) and environmental factors (weather change, food and aeroallergens) [1,2,15,16]. Major components in immune dysregulation include Langerhans' cells, inflammatory dendritic epidermal cells, monocytes, macrophages, lymphocytes, mast cells and keratinocytes. All of these components interact through an intricate cascade of cytoki