Spring Meeting of the Irish Association of Dermatologists. Friday 24th April 2009

Obesity has emerged as a major co-morbidity in patients with psoriasis. In a case control study we found that patients with psoriasis had significantly higher body mass indices (BMI) compared to controls (p = 0.004). Increased adiposity and weight gain were strong risk factors for the development of psoriasis in the Nurses Health study 1. Multivariate analysis demonstrated a clear, graded association between BMI and the risk of having psoriasis 1. Adipose tissue actively secretes cytokines such as TNF-alpha and interleukin-6 and pro-inflammatory adipokines such as leptin and resistin along with adiponectin which has anti-inflammatory effects. Patients with psoriasis had raised levels of serum resistin compared to controls 2. Serum levels were also correlated with psoriasis disease activity and were unrelated to BMI suggesting a link between psoriasis and adipokines. A second study of 39 patients found disease severity was correlated with insulin resistance and serum resistin. Recent studies have shown that patients who are obese have lower levels of natural killer (NK) cells when compared to controls. Natural killer cells from obese patients also had decreased levels of in-vitro activity compared to lean controls. Natural killer cells are thought to be involved in the pathogenesis of psoriasis and patients have lower levels of circulating NK cells than controls. We have investigated levels of circulating NK cells in obese and lean patients with psoriasis, their in vitro cytotoxcicity and also the effect of the adipokines leptin, adiponectin, resistin and cigarette smoke extract on the cytotoxcicity of circulating NK cells. CD 56; a marker of NK and NK-T cells; cells have been extracted from peripheral blood monocytes (PBMCs) of patients with psoriasis with magnetic beads. Using ethidium bromide and UV microscopy these CD 56 cells were counted. Psoriasis patients who are obese, defined as BMI > 30 (N = 6) have on average 3.84% CD 56 of total PBMCs cells versus patients who are lean defined as BMI < 25 (N = 7) have on average 8.9% CD56 cells (p = 0.02). CD 56 cells isolated above from PBMCs of patients with psoriasis and also controls were incubated with the myelogenous tumour line K562 in the presence of the adipokines resistin, leptin and adiponectin and also cigarette smoke extract for four hours. Using 7-AAD staining, the numbers of killed tumour cells were counted by flow cytometry and gating on the tumour cells. In the presence of resistin tumour killing by CD …