The Expression of Histamine Receptors in Skin Lesions of MRL/MP- lpr/lpr Mice

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease accompanied with systemic organs disorder including skin changes. The MRL/MP-lpr/lpr (MRL/l) mouse is a model of human LE. MRL/l mice skin lesions exhibit a decreased activity in histamine-N-methyltransferase (HMT) and impaired histamine metabolism. In order to clarify the role of histamine receptors (HRs) including H1R, H2R and H3R in MRL/l skin lesions, the relationship between HRs and skin lesions was assessed by immunohistochemical staining and RT-PCR methods. The expression of H2R was seen in the non-lesional skin of 2-month-old (mo) MRL/l mice; H2R expression continued for a couple of months, and then decreased in the skin lesions of 5-mo MRL/l mice. In MRL/l skin lesions, a dense mast cell infiltration expressed H2R was seen. In conclusion, an increased expression of H2R in mast cells may be associated with histamine metabolism in skin lesions from MRL/l mice.