Balance of Treg versus T-effector cells during systemic treatment with adalimumab and topical treatment with calcipotriol-betamethasone dipropionate ointment

Diminished suppressive capacity of regulatory T cells (Treg) has been demonstrated in blood and in lesional skin of psoriatic patients. Treatment with anti-TNF restored the number and function of circulating Treg in psoriasis. We aimed to study Treg in the skin of psoriatic patients undergoing topical treatment with calcipotriol-betamethasone dipropionate (CBD) ointment (n=12) or systemic treatment with anti-TNF agent adalimumab (n=10). Skin biopsies were collected from patients with chronic plaque psoriasis who responded to the above-mentioned treatments with a SUM-score improvement of at least 50% (at the end of treatment). Biopsies were processed for immunohistochemistry. As Treg function is associated with a numerical balance between Treg and effector T cells, Foxp3/CD4 ratios were calculated. It appeared that both treatments cause a significant decrease in the presence of Foxp3+ cells. However, in patients that were treated with CBD ointment, we observed lower Foxp3/CD4 ratios after 8weeks of treatment compared to baseline (t=0: 0.41 +/- 0.08; t=8: 0.22 +/- 0.04, P=0.033), whereas in patients who were treated with adalimumab we observed an increase of the Foxp3/CD4 ratios after 1.5 and 16weeks of treatment compared to baseline (t=0: 0.25 +/- 0.04; t=1.5: 0.32 +/- 0.06; t=16: 0.49 +/- 0.10, P=0.15). Based on Foxp3/CD4 ratios, we can conclude that adalimumab treated skin differs from CBD treated skin with regard to the anti-inflammatory/inflammatory balance. We suggest that, in contrast to CBD ointment, adalimumab favours local Treg function in the skin.