Elevated cutaneous expression of stem cell factor in chronic spontaneous urticaria: a prospective cohort study.

Background: Tissue expression of endothelial cell markers of microcirculatory changes in chronic spontaneous urticaria (CSU) is poorly understood.

Objectives: To explore the expression of specific endothelial cell markers [stem cell factor (SCF), vascular endothelial growth factor (VEGF) and membrane attack complex (MAC)] in lesional and nonlesional CSU skin through immunohistochemistry (IHC) and in serum.

Methods: Lesional and nonlesional skin biopsies from patients with CSU (n = 23) and healthy controls (n = 9) were studied by IHC for expression of SCF, VEGF and MAC. In this population, we also investigated blood levels of VEGF and SCF. Patients were also assessed for clinical characteristics, disease activity and markers of autoimmune CSU. The study was registered at ClinicalTrials.gov (NCT03443362).

Results: Epidermal SCF reactivity was significantly higher in CSU lesional skin than in healthy skin (P = 0.026). In the dermis, SCF immunoreactivity was seen particularly in endothelial, perivascular and epithelial cells. In CSU lesional skin, the mean perivascular SCF staining was significantly more intense than in healthy controls (P < 0.001). Furthermore, CSU nonlesional skin also showed significantly higher SCF staining in dermal perivascular cells than in healthy controls (P < 0.001). Patients with CSU had the highest SCF immunoreactivity scores in the epidermis and/or on dermal endothelial cells. These patients did not have significantly higher SCF serum levels.

Conclusions: To our knowledge, this is the first study to show elevated cutaneous expression of SCF in CSU. These findings underline the potential therapeutic possibilities of anti-Kit antibodies in CSU treatment.