Association between Contact allergy and Psoriasis

Nannie Bangsgaard

Abstract

6. SUMMERY
6.1 Summery in English Allergic contact dermatitis (ACD) and psoriasis are the two most prevalent skin diseases in the western world. ACD is the clinical manifestation of contact allergy. Contact allergy and psoriasis are both due to inflammatory mechanisms involving the innate and adaptive immune system. Psoriasis is conceived to be an autoimmune disease. Recent studies have suggested an inverse relation between contact allergy and autoimmune diseases.
The association between contact allergy and psoriasis could reveal mechanistic insights into both inflammatory processes.
The overall aim of this PhD study was to investigate the association between contact allergy and autoimmune disease, with focus on psoriasis. The work was done in three study parts. Part I Epidemiological studies. Part II Sensitization study and Part III Experimental studies. In part I the association between contact allergy and psoriasis was investigated in two conceptually different epidemiological studies, a patient register-based study and a population-based study. A significant inverse relation between contact allergy and psoriasis was found in both studies with odds ratio for a person with a psoriasis diagnosis
of having a positive patch-test of 0. 58 (CI 95% 0. 49 - 0.68) and 0.64 (CI 95% 0.42 - 0.98) respectively. Part II was undertaken in order to investigate the potential of hapten sensitization and reactivity to challenge in patients with autoimmune disease. In a sensitization study using the strong hapten Diphenylcyclopropenone (DPCP) five groups of patients were induced
and challenged: psoriasis, diabetes type I, mono-allergy, poly-allergy and healthy controls. Sensitisation ratios of patients with psoriasis and diabetes type I were significantly lower than healthy controls, with odds ratios of 0.18 (CI 95% 0. 039 - 0.85) P=0.031 and 0.74 (95% CI 0.548 – 1.008) P= 0.056 respectively. Sensitisation ratios of mono-allergic, polyallergic and healthy controls were equal.
38 A trend towards a lower reactivity in the psoriatic group and a higher reactivity in the polyallergic group was found. A significantly lower challenge threshold was found in the polyallergic group compared to the healthy and mono-allergic group, with p=0.005 and p=0.037 respectively.
In part III mechanisms behind the reduced reactivity seen in patients with psoriasis were investigated. Using biopsies from challenge sites, the possibility of down-regulatory events in the elicitation phase was investigated. No regulatory FoxP3+ T cells were found in challenge sites from non-responders on immunohistochemical staining and no significant changes in mRNA expression were found with microarray analysis. This indicates that non-responding was not due to an active down-regulation at the challenge site in patients with psoriasis or healthy controls. In conclusion the studies have contributed with evidence to support the theory that autoimmune diseases are inversely related to contact allergy. The studies have demonstrated that patients with autoimmune diseases have a reduced sensitization potential and suggest that this is not due to down-regulatory events in the elicitation phase.
OriginalsprogEngelsk
ISBN (Trykt)978-87-92613-06-6
StatusUdgivet - 2011

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