NGF topical application in patients with corneal ulcer does not generate circulating NGF antibodies

Nerve growth factor (NGF) is the prototype of the neurotrophin family and promotes the survival of specific populations of neurons, stimulates their morphological differentiation and regulates neuronal gene expression. Since its discovery, NGF attracted clinicians for its potential application in the treatment of neurological disorders. Recent studies demonstrated murine NGF eye drops may be successfully used to treat neurotrophic keratopathy. Neurotrophic keratopathy is a degenerative corneal disease caused by an impairment of the trigeminal nerve, which leads to corneal epithelial defect, ulcer, and perforation. NGF topical application induced complete ulcer healing and a recovery of the corneal sensitivity. The intent of this study is to address the question if murine NGF topical treatment stimulates the production of circulating anti-NGF antibodies. We evaluated patients with neurotrophic keratopathy who underwent topical therapy with NGF eye drops for possible ocular or systemic adverse effects in the course of 16-72 months follow up. None of the patients suffered any adverse reaction, except for mild and transient conjunctival hyperaemia and photophobia. Moreover, none of the treated patients developed circulating antibodies to NGF.