Department of Dermatology and Plastic Surgery,
1-1-1 Honjo, Kumamoto, Japan
Objective: To investigate the relationship between M2 macrophages and disease activity in SLE.
Methods: The expression of CD163, an M2 macrophage marker, in skin specimens was evaluated by immunohistochemistry. Quantitative real-time polymerase chain reaction was performed to determine mRNA expression of CD163 in the skin section. Serum levels of soluble CD163 were measured in 20 SLE patients and 12 healthy controls with specific enzyme-linked immunosorbent assays.
Results: The number of CD163-positive M2 macrophages and the mRNA levels of CD163 in the skin of SLE patients was significantly increased. SLE patients had significantly higher serum sCD163 levels than healthy controls. By analysis of the association between serum sCD163 levels and the clinical/laboratory features, we found that patients with elevated serum sCD163 levels showed significantly higher levels of anti-double-strand-DNA antibodies and higher prevalence of leukopenia than those with normal levels.
Conclusion: Infiltration of CD163-positive M2 macrophages was increased in SLE skin and sCD163 levels were increased in SLE sera. A systemic increase of sCD163 as well as local overexpression of CD163 in SLE patients indicate that M2 macrophages may play a role in the pathogenesis of SLE. Serum sCD163 levels may be a useful marker for disease severity in patients with SLE.