Osteopontin expression in chronic plaque psoriasis: an association with the severity of disease.

Objective: To explore the possible role of osteopontin (OPN) in chronic plaque psoriasis and understand the role of inflammation in psoriasis.
Study Design: We investigated 36 patients with chronic plaque psoriasis using immunohistochemical technique for evaluation of OPN immunolocalization compared to normal skin biopsies of 10 normal subjects representing the control group.
Results: OPN was expressed in the epidermis of all specimens, both in the psoriasis group and the control group without any significant differences except for the tendency of psoriatic lesions to show more cytoplasmic and nuclear pattern of OPN staining (55.56%) compared to normal skin (20%). Epidermal strong and diffuse immunostaining of OPN was associated with the severity of psoriasis, and there was a correlation of the intensity of OPN expression with the density of the dermal inflammatory infiltrate.
Conclusion: Our study suggests that OPN is involved in the pathophysiology of psoriasis, and a possible association with disease severity. OPN acts by different mechanisms through its expression by lesional keratinocytes, inflammatory cells, and endothelial cells. Nuclear localization of OPN may have a more significant role in the pathogenesis of psoriasis.