Chernyavsky_2012_Wound.Repair.Regen_20_103

It is well established that auto/paracrine acetylcholine (ACh) is essential for wound epithelialization, and that the mechanisms include regulation of keratinocyte motility and adhesion via nicotinic ACh receptors (nAChRs). Keratinocyte nAChRs can be also activated by non-canonical ligands, such as secreted mammalian Ly-6/urokinase-type plasminogen activator receptor-related protein (SLURP)-1 and -2. In this study, we determined effects of recombinant (r)SLURP-1 and-2 on migration of human epidermal and oral keratinocytes under agarose and epithelialization of cutaneous and oral mucosal excisional wounds in mice, and also identified nAChRs mediating SLURP signals. Both in vitro and in vivo, rSLURP-1 decreased and SLURP-2 increased epithelialization rate. The mixture of both peptides accelerated epithelialization even further, indicating that their simultaneous signaling renders an additive physiologic response. The specificity of rSLURP actions was illustrated by similar effects on cutaneous and oral wounds, which feature distinct responses to injury, and also by abrogation of rSLURP effects with neutralizing antibodies. rSLURP-1 acted predominantly via the alpha7 nAChR-coupled up-regulation of the sedentary integrins alpha2 and alpha3 , whereas SLURP-2--through alpha3, and alpha9 nAChRs up-regulating migratory integrins alpha5 and alphaV . The biologic effects of rSLURPs required the presence of endogenous ACh, indicating that auto/paracrine SLURPs provide for a fine tuning of the physiologic regulation of crawling locomotion via the keratinocyte ACh axis. Since nAChRs have been shown to regulate SLURP production, cholinergic regulation of keratinocyte migration appears to be mediated by a reciprocally arranged network. The cholinergic peptides, therefore, may become prototype drugs for the treatment of wounds that fail to heal.