A Vicious NGF-p75NTR Positive Feedback Loop Exacerbates the Toxic Effects of Oxidative Damage in the Human Retinal Epithelial Cell Line ARPE-19

Int J Mol Sci. 2023 Nov 12;24(22):16237. doi: 10.3390/ijms242216237.

Abstract

In spite of its variety of biological activities, the clinical exploitation of human NGF (hNGF) is currently limited to ocular pathologies. It is therefore interesting to test the effects of hNGF in preclinical models that may predict their efficacy and safety in the clinical setting of ocular disorders and compare the effects of hNGF with those of its analogs. We used a human retinal pigment cell line, ARPE-19 cells, to investigate the effects of hNGF and its analogs, mouse NGF (mNGF) and painless NGF (pNGF), on cell viability under basal conditions and after exposure to oxidative stimuli, i.e., hydrogen peroxide (H2O2) and ultraviolet (UV)-A rays. The effects of hNGF and pNGF were also tested on the gene expression and protein synthesis of the two NGF receptor subtypes, p75 neurotrophic receptors (p75NTR) and tyrosine kinase A (TrkA) receptors. We drew the following conclusions: (i) the exposure of ARPE-19 cells to H2O2 or UV-A causes a dose-dependent decrease in the number of viable cells; (ii) under baseline conditions, hNGF, but not pNGF, causes a concentration-dependent decrease in cell viability in the range of doses 1-100 ng/mL; (iii) hNGF, but not pNGF, significantly potentiates the toxic effects of H2O2 or of UV-A on ARPE-19 cells in the range of doses 1-100 ng/mL, while mNGF at the same doses presents an intermediate behavior; (iv) 100 ng/mL of hNGF triggers an increase in p75NTR expression in H2O2-treated ARPE-19 cells, while pNGF at the same dose does not; (v) pNGF, but not hNGF (both given at 100 ng/mL), increases the total cell fluorescence intensity for TrkA receptors in H2O2-treated ARPE-19 cells. The present findings suggest a vicious positive feedback loop through which NGF-mediated upregulation of p75NTR contributes to worsening the toxic effects of oxidative damage in the human retinal epithelial cell line ARPE-19. Looking at the possible clinical relevance of these findings, one can postulate that pNGF might show a better benefit/risk ratio than hNGF in the treatment of ocular disorders.

Keywords: ARPE-19 cells; H2O2; TrkA receptors; UV-A; human NGF; mouse NGF; p75NTR receptors; painless NGF.

MeSH terms

  • Animals
  • Cell Line
  • Epithelial Cells / metabolism
  • Feedback
  • Humans
  • Hydrogen Peroxide* / pharmacology
  • Mice
  • Nerve Growth Factor / metabolism
  • Nerve Growth Factor / pharmacology
  • Oxidative Stress
  • Receptor, Nerve Growth Factor / metabolism
  • Receptor, trkA* / metabolism
  • Receptors, Nerve Growth Factor / metabolism

Substances

  • Receptor, trkA
  • Hydrogen Peroxide
  • Nerve Growth Factor
  • Receptors, Nerve Growth Factor
  • Receptor, Nerve Growth Factor

Grants and funding

This research was funded by internal funding from UCSC (Fondi di Ateneo D1: 2021–2022) to GT. The contribution of financial support in the form of “Ricerca Corrente 2023” from Fondazione Policlinico Universitario “A. Gemelli” IRCCS to G.T. is acknowledged. This work was also supported by the “Fondo Ordinario Enti” (FOE D.M 865/2019) in the framework of a collaboration agreement between the Italian National Research Council and EBRI. We thank the EBRI’s Facility NGF Lab for providing the anti-TrkA antibody, MNAC13.