NGF and systemic lupus erythematosus: The relationship between neurotrophins and immune-mediated phenomena was initially envisioned by Aloe et al. (85) and Bracci-Laudiero et al. (86) who reported elevated levels of NGF in the synovial fluid of patients with chronic arthritis and in sera from patients with systemic lupus erythematosus (SLE), in the latter case positively correlated with disease severity.