Osteopontin expression in psoriasis versus lichen planus: a comparative immunohistochemical study

BackgroundPsoriasis is a complex immune-mediated chronic inflammatory disorder triggered by various risk factors in genetically susceptible individuals, while lichen planus (LP) is a chronic inflammatory, immune-mediated disease. Osteopontin (OPN) is a phosphorylated acidic glycoprotein produced by several cell types and involved in immune regulation, cellular signaling, inflammation, and vascularization, and plays a role in various physiological and pathological processes. While the literature has many studies regarding OPN expression in psoriasis and oral lichen, no studies were done on cutaneous LP. Furthermore, no comparison between psoriasis and cutaneous LP was made.ObjectiveTo evaluate OPN expression in psoriasis versus LP as the most common papulosquamous skin disorders in comparison with healthy patients to study its possible role in the pathogenesis of both diseases.Patients and methodsThis comparative study included 40 patients with psoriasis and 40 patients with LP, in addition with 20 healthy individuals as the control group. Skin biopsies were obtained and stained with H and E. Immunohistochemical staining of sections was performed using a human polyclonal anti-OPN IgG antibody to evaluate epidermal and dermal OPN expression in psoriasis and LP sections versus control.ResultsThere was a statistically significant decrease in epidermal OPN expression in the patients of both diseases when compared with the control group, but a statistically significant increase in the dermal expression of OPN in both diseases when compared with the control group. In addition, a statistically significant increase in OPN expression was detected in the epidermis of the psoriasis group in comparison with the lichen group. Higher expression of dermal OPN expression is related to severity of the psoriasis area severity index score in psoriasis patients and to the lichen planus severity index in LP.ConclusionDue to its significant dermal expression in psoriasis and LP immunohistochemically stained sections, OPN might have an essential role in the pathogenesis of both diseases, and the level of its expression in tissues could indicate the severity of psoriasis and LP.