VEGF is likely a key factor in the link between inflammation and angiogenesis in psoriasis: Results of an immunohistochemical study

Psoriasis is a chronic skin disease, characterized by epidermal hyperplasia, inflammation, angiogenesis and vascular remodelling. An immunohistochemical study on fifteen cryosections of psoriatic skin was performed using antibodies against VEGF, HIF1-alpha, CD34, Factor VIII, MMP-2, MMP-9, TIMP-1 and TIMP-2. Psoriatic skin showed a diffuse VEGF positive staining (13.15 +/- 6.6), while no expression was observed in normal epidermis. No or faint HIF-1 alpha immunostaining was detected in healthy skin, while in psoriatic skin HIF-1 alpha was diffusely expressed. A positive correlation between HIF-1 alpha and VEGF was reported in psoriatic skin (r = 0.644; p = 0.010). In psoriatic sections CD34 expression was significantly higher in respect to control skin (19.15 +/- 12.61 vs 3.0 +/- 0.23; p = 0.04), factor VIII immunostaining also demonstrated a significant increased development of the microvasculature in comparison with healthy skin (18.39 +/- 8.16 vs 7.4 +/- 0.20; p = 0.033). Total MMP-2 expression of healthy skin (30 +/- 2.26) was significantly lower in respect to the MMP-2 psoriatic skin (71.5 +/- 4.13; p = 0.0001) and a positive correlation was observed between VEGF and MMP-2 in psoriatic patients (r = 0.688; p = 0.046). In psoriatic skin MMP-9 expression was significantly increased in comparison to control skin (31 +/- 0.3 vs 8 +/- 6.1; p = 0.007). All cases of psoriatic skin tissue showed that TIMP-2 and TIMP-1 expression statistically decreased in psoriatic skin (respectively 11 +/- 1.2 and 12 +/- 1.5) in comparison with healthy skin (respectively 15 +/- 3.2 and 53 +/- 3.8; p = 0.0001). In conclusion, we observed that VEGF overexpression correlated with HIF-1 alpha and MMP-2 expression, underlining the role of VEGF in psoriasis as a key factor in the link between inflammation and angiogenesis.