Psoriatic Keratinocytes Express High Levels of Nerve Growth Factor
Siba P. Raychaudhuri, Wen-Yue Jiang, Eugene M. Farber
Many investigators have reported proliferation of terminal cutaneous nerves and upregulation of various neuropeptides (substance P, vasoactive intestinal polypeptide, calcitonin gene-related peptide) in psoriatic lesions. Nerve growth factor promotes growth of nerves and causes upregulation of neuropeptides like substance P and calcitonin gene-related peptide.
In this study we investigated the expression of nerve growth factor in psoriatic lesions, non-lesional psoriatic skin, lichen planus and normal control skin. Immunoperoxidase staining was applied on cryosections prepared from snap-frozen biopsy specimens. The primary antibody used was a polyclonal anti-NGF-β antibody. Nerve growth factor was detected only in the keratinocytes. In psoriatic tissue the number of keratinocytes per square millimeter of epidermis positive for nerve growth factor was 84.7±46.3 compared to 44.8±29.9, 18.9±11.8 and 7.5±16.9, respectively, in non-lesional psoriatic skin, normal skin and lichen planus.
Increased expression of nerve growth factor substantiates larger numbers of terminal cutaneous nerves and upregulations of substance P and calcitonin gene-related peptide in psoriatic lesions. In addition, nerve growth factor is mitogenic to keratinocytes, activates T-lymphocytes and can induce migration of inflammatory cellular infiltrates, histological features characteristic of psoriasis.