Manganese(III) tetrakis(1-methyl-4-pyridyl) porphyrin, a superoxide dismutase mimetic, reduces disease severity in in vitro and in vivo models for dry-eye disease

Ocul Surf. 2019 Apr;17(2):257-264. doi: 10.1016/j.jtos.2019.02.006. Epub 2019 Feb 23.

Abstract

Purpose: To determine the efficacy of the superoxide dismutase mimetic, manganese(III) tetrakis(1-methyl-4-pyridyl) porphyrin (Mn-TM-2-PyP), in vitro in human corneal epithelial (HCE-T) cells and in vivo in a preclinical mouse model for dry-eye disease (DED).

Methods: In vitro, HCE-T cultures were exposed either to tert-butylhydroperoxide (tBHP) to generate oxidative stress or to hyperosmolar conditions modeling cellular stress during DED. Cells were pre-treated with Mn-TM-2-PyP or vehicle. Mn-TM-2-PyP permeability across stratified HCE-T cells was assayed. In vivo, Mn-TM-2-PyP (0.1% w/v in saline) was delivered topically as eye drops in a desiccating stress/scopolamine model for DED. Preclinical efficacy was compared to untreated, vehicle- and ophthalmic cyclosporine emulsion-treated mice.

Results: Mn-TM-2-PyP protected HCE-T cells in a dose-dependent manner against tBHP-induced oxidative stress as determined by calculating the IC50 for tBHP in the resazurin, MTT and lactate dehydrogenase release cell viability assays. Mn-TM-2-PyP did not protect HCE-T cells from hyperosmolar insult. Its permeability coefficient across a barrier of HCE-T cells was 1.1 ± 0.05 × 10-6 cm/s and the mass balance was 62 ± 0.6%. In vivo, topical dosing with Mn-TM-2-PyP resulted in a statistically significant reduction of corneal fluorescein staining, similar to ophthalmic cyclosporine emulsion. Furthermore, Mn-TM-2-PyP significantly reduced leukocyte infiltration into lacrimal glands and prevented degeneration of parenchymal tissue. No protective effect against loss of conjunctival goblet cells was observed. Notably, Mn-TM-2-PyP did not produce ocular toxicity when administered topically.

Discussion: Our data suggest that Mn-TM-2-PyP, a prototypic synthetic metalloporphyrin compound with potent catalytic antioxidant activity, can improve signs of DED in vivo by reducing oxidative stress in corneal epithelial cells.

Keywords: Antioxidant; Cornea; Corneal epithelial cells; Dry eye disease; Keratoconjunctivitis sicca; Lacrimal gland; Manganese porphyrin; Oxidative stress.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antioxidants
  • Cell Count
  • Disease Models, Animal
  • Dry Eye Syndromes / drug therapy*
  • Dry Eye Syndromes / metabolism
  • Dry Eye Syndromes / pathology
  • Goblet Cells / drug effects
  • Goblet Cells / pathology*
  • Humans
  • Metalloporphyrins / administration & dosage*
  • Mice
  • Mice, Inbred C57BL
  • Ophthalmic Solutions / administration & dosage
  • Oxidative Stress*
  • Severity of Illness Index

Substances

  • Antioxidants
  • Metalloporphyrins
  • Ophthalmic Solutions
  • manganese (III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin