Estrogen receptors in giant cell arteritis. An immunocytochemical, Westernblot and RT-PCR study

Objective Giant cell arteritis (GCA) is a chronic form of vasculitis which predominan tly affects women over 50 years of age. The aim of this study was to analys e the presence of estrogen receptor a (ER) in the temporal arteries of pati ents with GCA. Methods Inflamed temporal artery biopsies from 43 GCA patients were stained with mo noclonal antibodies to two different segments of the ER and compared with n on-inflamed arteries from age- and sex-matched controls who had not receive d a clinical diagnosis of GCA. The protein that was extracted from 4 GCA-po sitive biopsies and 4 non-GCA controls was analysed using the Western blot method with a monoclonal antibody to ER. Reverse transcriptase-polymerase c hain reaction (RT-PCR) analysis using primer pairs specific to ER-cDNA was performed on the total RNA from 4 GCA-positive biopsies and 4 non-GCA contr ols. Results The inflamed arteries expressed distinct cytoplasmic immunoreactivity to ER in activated mononuclear inflammatory cells and in giant cells. Biopsies f rom GCA patients and controls displayed cytoplasmic ER positivity in smooth muscle cells. Western blot analysis revealed two bands corresponding to ap proximately 64 and 54 kDa, respectively, in the inflamed arteries and contr ols. In the inflamed biopsies and non-GCA controls, RT-PCR analysis reveale d a strong band corresponding to approximately 670 bp, as expected, and a w eaker band corresponding to approximately 440 bp. Conclusion In inflamed arteries from GCA patients, smooth muscle cells, activated mono nuclear inflammatory cells and giant cells express cytoplasmic ER. Non-infl amed control arteries also express cytoplasmic ER in smooth muscle cells. T he accumulation of cytoplasmic ER may suggest the involvement of estrogen n ot only in GCA but also in normal vascular aging The results justify furthe r investigations into the pathogenetic roles of estrogen metabolism in GCA.