Background: The autoimmune skin disease bullous pemphigoid (BP) is characterized by subepidermal blister formation and a strong dermal infiltrate of mononuclear cells and eosinophils as well as a T-helper (Th) 2-dominated cytokine milieu. CCL18 is a chemokine, with unknown receptor counterpart, frequently associated with inflammatory Th2-type responses.
Objectives: The study was performed to investigate an association of CCL18 with BP.
Methods: CCL18 was determined by enzyme-linked immunosorbent assay in serum and blister fluid of patients with BP, pemphigus vulgaris and healthy individuals. In vitro chemotaxis assays were performed to demonstrate migration of peripheral blood mononuclear cells to BP blister fluid. Immunohistology and immunofluorescence staining were used to evaluate CCL18 expression in skin.
Results: We have found that the levels of CCL18 in sera from patients with BP are 84% higher than those normally observed in healthy individuals. In addition, blister fluid of patients with BP is extremely rich in CCL18, reaching concentrations which are fivefold and sevenfold higher than those found in the sera of patients with BP and healthy individuals, respectively. Using immunofluorescence techniques we identified Langerhans cells, antigen-presenting cells of the dermis and eosinophils as producers of CCL18 in BP skin. We studied the possibility of using CCL18 expression as a biomarker linked to BP by monitoring the serum levels of CCL18 and the disease course of nine patients with BP over a maximum period of 54 months. In this study, CCL18 levels correlated with the disease course in most of the patients.
Conclusions: Our data implicate CCL18 as a functionally relevant chemokine in BP, mediating recruitment of blood mononuclear cells into the hallmark infiltrated skin lesion. The high correlation of CCL18 expression and BP disease suggests that blood levels of this chemokine can be used as an easy method to monitor disease progression and/or efficacy of therapeutic interventions.