Association of anti-triosephosphate isomerase antibodies with aseptic meningitis in patients with neuropsychiatric systemic lupus erythematosus

Autoantibodies to triosephosphate isomerase (TPI), which is an important glycolytic enzyme in red blood cells and neuronal cells, have been reported to be associated with neuropsychiatric systemic lupus erythematosus (NPSLE) pathogenesis. However, the clinical features regarding anti-TPI antibody (anti-TPI)-positive NPSLE are not yet known. The aim of this study is to investigate the clinical features of anti-TPI-positive NPSLE patients using anti-TPI index values determined by enzyme-linked immunosorbent assay (ELISA). Thirty-one NPSLE patients treated in our department were included in this study. Serum samples were collected, and serum anti-TPI titers were measured by ELISA. The anti-TPI index values were defined as follows: (OD₄₀₅ of samples - OD₄₀₅ of negative control)/(OD₄₀₅ of positive control - OD₄₀₅ of negative control) × 100. Anti-TPI index values greater than 2 standard deviations above the mean of healthy controls were regarded as positive. The clinical features of anti-TPI-positive and anti-TPI-negative NPSLE were compared. Ten of the 31 NPSLE patients had anti-TPI positivity (32.3%). The clinical features of anti-TPI-positive NPSLE were comparable with those of anti-TPI-negative NPSLE, except for a higher frequency of aseptic meningitis (p = 0.027) and a lower frequency of acute confusional state (P = 0.026). Laboratory data in patients with anti-TPI-positive NPSLE showed significantly higher serum IgG levels. Furthermore, anti-TPI index values positively correlated with serum IgG levels. Our study indicates that serum anti-TPI increases in the presence of elevated IgG levels and can be associated with the pathogenesis of aseptic meningitis in NPSLE.