NGF and rheumatoid arthritis: Intriguingly, in RA, there appears to be an expansion of perivascular sub-lining THY1+ fibroblasts and a concomitant retraction of sensory nerve fibres from the lining into the sub-lining layer.7 27 It is thus feasible that nerve fibres are attracted to move back into the sub-lining by perivascular and fibroblast-derived neurotrophic mediators such as NGF (figure 1).