July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Cleavage of FITC-tagged N-acetylmuramyl-L-alanine-D-isoglutamine by rabbit tears.
Author Affiliations & Notes
  • Peter Lam
    Ophthalmology, LSUHSC-Shreveport, Shreveport, Louisiana, United States
  • Maxwell Burch
    Ophthalmology, LSUHSC-Shreveport, Shreveport, Louisiana, United States
  • Thomas Redens
    Ophthalmology, LSUHSC-Shreveport, Shreveport, Louisiana, United States
  • Chanping Liang
    Ophthalmology, LSUHSC-Shreveport, Shreveport, Louisiana, United States
  • Marlyn P Langford
    Ophthalmology, LSUHSC-Shreveport, Shreveport, Louisiana, United States
  • Footnotes
    Commercial Relationships   Peter Lam, None; Maxwell Burch, None; Thomas Redens, None; Chanping Liang, None; Marlyn Langford, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 6256. doi:
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    • Get Citation

      Peter Lam, Maxwell Burch, Thomas Redens, Chanping Liang, Marlyn P Langford; Cleavage of FITC-tagged N-acetylmuramyl-L-alanine-D-isoglutamine by rabbit tears.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6256.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Mammalian serum has been shown to contain N-acetylmuramyl-L-alanine amidase (NAMAA; cleaves muramyl dipeptide), an enzyme reported to inhibit the pro-inflammatory activity of bacterial peptidoglycan. This study was undertaken to determine if NAMAA occurs in rabbit tears and to determine if it is increased during the extraocular inflammatory response in rabbits.

Methods : Commercially available fluorescein-isothiocynate tagged muramyl dipeptide (MDPFITC) (MDP induces inflammation via activation of the nucleotide-binding oligomerization domain-like receptor (NOD)] was reacted with tears collected from rabbits pre and post topical application of NOD ligand. Utilizing MDPFITC cleavage followed by agarose gel electrophoresis the NAMAA activity in tears and serum from 6 rabbits, collected at times pre- and post-topical NOD1 ligand-induction of conjunctivitis (IOVS 2018;59:ARVO E-Abstract 2262), was quantified densitometrically and characterized.

Results : Agarose gel electrophoresis of MDPFITC incubated with serum or tear fluid separated the cleaved free FITC tagged muramic acid moiety (MAFITC) from the MDPFITC. Tears and serum, collected at times pre- and post NOD1 ligand induction of conjunctivitis in rabbits, cleaved MDPFITC in a time and dose-dependent manner. Pre-treatment serum and unstimulated tears (5 µl) cleaved 97±28 ng and 13±6.5 ng MDPFITC/20h, respectively. The mean amount of MDPFITC cleavage by ipsilateral tear samples tended to be higher than in contralateral eyes collected at 0 (20±11 vs. 23±10 ng), 8 (19±7 vs. 25±9 ng), and 24 h (17.8±10 vs. 18±8 ng/5µl/20 h) post NOD-induced conjunctivitis, respectively, but were not significantly different.

Conclusions : We report a method for the detection of a NAMAA-like activity in rabbit serum and tears utilizing FITC coupled MDP. The rabbit tear NAMAA-like activity is constitutively produced and was not significantly increased in acute tears from eyes with NOD-ligand induced inflammation.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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