TNF and systemic lupus erythematosus: Results showed that the serum concentration of PGRN was correlated with the levels of IL-6 (r = 0.790, P < 0.01), TNFR (r = 0.559, P = 0.01), TNF-α (r = 0.438, P = 0.015) and anti-dsDNA antibody (r = 0.906, P < 0.01) in the serum of pre-treatment SLE patients (Figure 2).