Skin homeostasis during inflammation: a role for nerve growth factor

Histol Histopathol. 2008 Jan;23(1):1-10. doi: 10.14670/HH-23.1.

Abstract

The skin is a neuroendocrine immune organ in which many different molecules operate in autocrine-paracrine manner to guarantee tissue homeostatsis in physiological and pathophysiological conditions. In this paper we examined NGF and p75 receptor expression in the skin, during CFA induced inflammation, in a time-course study. We also examined cutaneus innervation and proliferation, by means of immunohistochemistry and quantitative image analysis, RT-PCR and Western blot. Spontaneous and evoked pain-behavior was also measured in experimental rats. The main results can be summarized as follows: 1). a peripheral sensory neuropathy develops in this condition, as indicated by thermal hyperalgesia, thus leading to a sensory denervation of the hind-paw skin as indicated by disappearance of CGRP and PGP9.5-IR fibers; 2). NGF and p75 expression (mRNA and protein) increases in the skin (keratinocytes) in the acute phase of CFA inflammation; 3). at this stage, a higher proliferative activity is observed in the skin, as defined by the expression of cell cycle-associated protein Ki67; 4). in the long-lasting chronic phase there is a further up-regulation of NFG and p75 expression in the skin; 5). trkA mRNA expression inversely correlates with p75 and NGF mRNA expression. These results suggest that CFA chronic inflammation evolves from inflammation to a small fibers sensory neuropathy and NGF seems to play a role in both events.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcitonin Gene-Related Peptide / metabolism
  • Freund's Adjuvant
  • Homeostasis / physiology*
  • Inflammation / chemically induced
  • Inflammation / metabolism*
  • Inflammation / pathology
  • Keratinocytes / metabolism
  • Keratinocytes / pathology
  • Male
  • Nerve Growth Factor / metabolism*
  • Neurons, Afferent / metabolism
  • Neurons, Afferent / pathology
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Nerve Growth Factor / metabolism
  • Receptor, trkA / metabolism
  • Skin / metabolism*
  • Skin / pathology

Substances

  • RNA, Messenger
  • Receptor, Nerve Growth Factor
  • Freund's Adjuvant
  • Nerve Growth Factor
  • Receptor, trkA
  • Calcitonin Gene-Related Peptide