NGF and dry eye syndrome: Fracture and/or immobilization induced mechanical allodynia, unweighting, warmth, and edema, in associations with an elevated release of TNF-α, IL-1β, IL-6, and NGF from KCs (Li et al., 2009, 2010; Wei et al., 2009a,b; Whitehead et al., 2012; Kingery, 2010; Guo et al., 2012, 2014).