Changes in serum interleukin-6 levels as possible predictor of efficacy of tocilizumab treatment in rheumatoid arthritis.

OBJECTIVES: We aimed to evaluate the association between the change in serum IL-6 during the clinical course of tocilizumab (TCZ) therapy and rheumatoid arthritis (RA) disease activity or occurrence of adverse events. METHODS: General laboratory data including serum IL-6 levels and physical findings were obtained every 4 weeks, and, in addition, at the time when any adverse events occurred. RESULTS: The proportion achieving Clinical Disease Activity Index (CDAI) remission at 52 weeks was significantly lower in 20 patients with serum IL-6 ≥ 30 pg/ml at 12 weeks than 24 patients with serum IL-6 < 30 pg/ml. In 17 patients with serum IL-6 ≥ 30 pg/ml at 24 weeks, the proportion achieving CDAI remission was also significantly lower than 27 patients with serum IL-6 < 30 pg/ml then. In these 17 patients, Disease Activity Score (DAS) 28-ESR and CDAI at 52 weeks were significantly higher than those with serum IL-6 < 30 pg/ml. Age- and sex-adjusted logistic regression analysis showed logIL-6 at 12 weeks to be a predictive factor for DAS28-ESR remission at 52 weeks. CONCLUSION: Serum IL-6 levels from 12 to 24 weeks after TCZ initiation better reflect the efficacy of TCZ at 52 weeks.

Factors related to elevated serum immunoglobulin G4 (IgG4) levels in a Japanese general population.

BACKGROUND: Elevated serum immunoglobulin G4 (IgG4) concentrations are one of the characteristic findings in IgG4-related disease (IgG4-RD). This study investigated the frequency of elevated serum IgG4 levels and associated factors in a general Japanese population. METHODS: Serum IgG4 concentrations were measured in 1,201 residents of Ishikawa prefecture who underwent general medical examinations. Factors associated with elevated serum IgG4 concentrations were assessed by logistic regression analysis. Participants with elevated serum IgG4 were subjected to secondary examinations. RESULTS: The mean serum IgG4 concentration was 44 mg/dL, with 42 (3.5%) participants having elevated serum IgG4 levels. Age- and sex-adjusted logistic regression analyses showed that male sex, older age, and lower intake of lipids and polyunsaturated fatty acids and higher intake of carbohydrates in daily diet were associated with elevated serum IgG4 concentration. Subgroup analyses in men showed that older age, lower estimated glomerular filtration rates based on serum cystatin C (eGFR-cysC) levels, and higher hemoglobin A1c (HbA1c) levels were associated with elevated serum IgG4 concentration. Analyses in women showed that lower intake of lipids and fatty acids and higher intake of carbohydrates were significantly associated with elevated serum IgG4 concentration. One of the 15 participants who underwent secondary examinations was diagnosed with possible IgG4-related retroperitoneal fibrosis. CONCLUSIONS: Elevated serum IgG4 levels in a Japanese general population were significantly associated with older age, male gender, and dietary intake of nutrients, with some of these factors identical to the epidemiological features of IgG4-RD.