Association of an insertion polymorphism of angiotensin-converting enzyme gene with the activity of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) shows various clinical manifestations, w hich are characterized by inflammation in many different organ systems. The cause of SLE is still unclear; however, the immunological abnormalities ar e considered to be responsible for the pathogenesis of SLE. As angiotensin I-converting enzyme (ACE) has been reported to be associated with various i mmunological phenomena, we investigated the correlation between insertion ( I)/deletion (D) polymorphism of the ACE gene and the disease activity of SL E. Ninety-three patients with newly diagnosed SLE were enrolled in this stu dy. AC-E genotype was determined by the polymerase chain reaction (PCR). We measured serum levels of anti-double-stranded (ds) DNA antibody (Ab) and s erum levels of total complements (CH50) as the parameter for lupus activity . Moreover, we evaluated the clinical disease activity by calculating SLE d isease activity index (SLEDAI). Individuals with II genotype showed a significant increase in SLE activity. Patients with the ACE II genotype showed a higher serum level of anti-dsDN A Ab (14.3 IU/ml (5.475, 74.6, median (25th centile, 75th Gentile)) than th ose with the DD genotype (4.65 IU/ml (4.05, 6.8)) (P<0.01). Moreover, patie nts with the II genotype also showed lower levels of serum CP50 than those with the DD genotype (P < 0.01). Patients with the ii or DI genotype had si gnificantly higher SLEDAI score than those with the DD genotype (P < 0.01). These results suggest that the ACE genotype could be associated with the d isease activity of SLE. ACE insertion polymorphism might be used as one of predictive factors for the activity of lupus.