Serum transglutaminase 2 activity as a potential biomarker of disease severity and response to omalizumab in chronic spontaneous urticaria

Dear Editor, Chronic spontaneous urticaria (CSU) is characterized by recurrent hives with or without angioedema lasting for more than 6 weeks; it affects 0.5 - 1% of the population worldwide. Although CSU is not a life-threatening condition, it has a large impact on quality of life. The basic treatment for CSU is second-generation H1 antihistamines (H1AH). However, approximately 50% of CSU are not controlled with H1AH, even with increasing doses. Cyclosporine and omalizumab - humanized monoclonal anti-IgE antibodies have been suggested as second or third-line therapies for CSU unresponsive to H1AH. However, there remain a substantial proportion of CSU patients that are not completely responsive to these drugs. We previously reported that transglutaminase 2 (TG2), an enzyme involved in the posttranslational modification of proteins by deamination and amine incorporation, plays an important role in CSU pathogenesis, showing high expression and release in human mast cells.