GABA and GABA(A) receptor expression on immune cells in psoriasis: a pathophysiological role.

Psoriasis is a chronic inflammatory disease in which pruritus is a common symptom. Pruritus may be associated with the gamma-aminobutyric acid (GABA) system. The distribution of GABA and its GABA(A) receptor (R) was studied in involved and non-involved psoriatic skin, as well as normal healthy control skin, using an immunohistochemistry technique. Pruritus was determined using a visual analog scale. Inflammatory cells immunoreactive for the GABA ligand and the GABA(A) R were increased (P < 0.01, respectively) in the involved skin. Cells stained for GABA ligand were mostly macrophages with some lymphocytes, while cells stained for GABA(A) R were macrophages, neutrophils or lymphocytes. There was a positive correlation when comparing GABA ligand (P = 0.05) and GABA(A) R (P < 0.05) expressing inflammatory cells, with pruritus. The GABA ligand and its GABA(A) R may play a role for the pathogenesis of psoriasis as well as for pruritus in this disease.