Increased serum levels and local expression of neutrophil gelatinase-associated lipocalin in generalized pustular psoriasis

Generalized pustular psoriasis (GPP) is not solely a skin condition but also a systemic disorder, in which innate immune systems are involved. Neutrophil gelatinase-associated lipocalin (NGAL) is a protein secreted by activated neutrophils, and is expressed in various tissues. In the present study, we investigated the role of NGAL by comparing its serum levels among patients with GPP, psoriasis vulgaris, palmoplantar pustulosis, and healthy controls. Serum NGAL concentration was significantly higher in the patients with active GPP than in the psoriasis vulgaris, palmoplantar pustulosis, and healthy controls. Interestingly, in the patients with GPP, higher serum NGAL levels positively correlated with disease severity. Moreover, GPP patients with liver dysfunction and type 2 diabetes exhibited higher NGAL concentration in the sera. In addition, local expression of NGAL was enhanced in the lesional skin of GPP. These findings suggest that NGAL is a key factor in the pathogenesis of GPP, and may function as a useful clinical biomarker for this systemic inflammatory condition.