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.