2.2 Contact Dermatitis
Contact dermatitis is a common inflammatory skin disorder; it is usually characterised by alternating relief and deterioration of symptoms but is sometimes persistent.27 It can be divided into irritant contact dermatitis (ICD), a non-immunologically driven inflammatory reaction to an irritating substance, and allergic contact dermatitis, a type IV delayed-type hypersensitivity reaction resulting from the activation of allergen-specific T cells, i.e. a second exposure to the allergen results in circulating memory T cells homing into the skin and eliciting an immunologic reaction that causes skin inflammation.28
Topical corticosteroid hormone treatment is typically the first-choice therapy for contact dermatitis. However, long-term use of corticosteroids, especially high-potency agents, can lead to side effects such as skin atrophy, telangiectasia, dermatoglyphics and pigmentation due to immune system and skin barrier damage. Therefore, new agents for effectively controlling contact dermatitis are required.
Oxidative stress is now known to play a key role in contact dermatitis inflammation. In particular, ROS participate in dendritic cell activation.29 As well as being an endogenous redox regulatory protein, Trx is an effective ROS scavenger.30Because ROS regulate the function of dendritic cells, which function in the sensitisation phase of contact hypersensitivity, transgenic overexpression of Trx1 and systemic administration of exogenous Trx1 can suppress skin inflammation through inhibition of neutrophil recruitment during the elicitation phase (but not during the induction phase) in mice treated with 2,4-dinitrofluorobenzene.31 Transgenic overexpression of Trx1 and the systemic administration of exogenous Trx1 can prevent cutaneous inflammation caused by UV radiation through the regulation of cellular redox status and ROS scavenging.32Previously, we demonstrated that Trx1 ameliorates ICD by inhibiting epithelial production and releasing inflammatory cytokines and chemokines.33 The exact therapeutic mechanism of Trx1 in contact dermatitis requires further clarification, but the existent research suggests that Trx1 could be used to treat the disorder.