Immunomodulator Galectin-9 is Increased in Blood and Skin of Patients with Bullous Pemphigoid
Jasper Pruessmann, Wiebke Pruessmann, Maike M. Holtsche, Beke Linnemann, Christoph M. Hammers, Nina van Beek, Detlef Zillikens, Enno Schmidt, Christian D. Sadik
Massive recruitment of eosinophils into the dermis is a hallmark of bullous pemphigoid pathogenesis. Identifying the chemoattractant(s) guiding eosinophils into the skin in bullous pemphigoid is a prerequisite to therapeutic targeting of eosinophil recruitment. Galectin -9 is a potent chemoattractant for eosinophils, but its potential role in bullous pemphigoid is unknown. The aim of this study was to determine the expression levels of galectin-9 in serum and skin of patients with bullous pemphigoid. Galectin-9 levels were significantly elevated in serum of patients with bullous pemphigoid compared with age- and sex-matched controls, but did not correlate with disease activity assessed with the Bullous Pemphigoid Disease Area Index. Galectin-9 expression was also increased in lesional skin of patients with bullous pemphigoid, and was expressed predominantly in eosinophils, neutrophils and keratinocytes. In conclusion, these results support the notion that galectin-9 may play a role in the pathogenesis of bullous pemphigoid.
Eosinophils are major culprit cells in bullous pemphigoid, but the mechanism of their recruitment into the skin is unknown. This study identified galectin-9 as a potential driver of eosinophil recruitment in bullous pemphigoid. The results also show that galectin-9 is a potential serum biomarker in bullous pemphigoid. This finding could lead to the development of composite biomarkers for the diagnosis of bullous pemphigoid from serum samples.