Abstract
Purpose: :
To demonstrate the cellular distribution of immunoreactive cross-linked glutamate (xGlu), Na+-dependent-high affinity excitatory amino acid transporter (EAAT1-5) subtypes, Na+-independent-low affinity Glu/cysteine (Xc) exchanger, GS (converts intracellular Glu to Gln) and GGT (converts extracellular glutathione and Gln to Glu) in human conjunctival cells.
Methods: :
The immunofluorescent antibody technique was used to demonstrate the co-localization of immunoreactive xGlu, EAAT1-5, Xc, GS and GGT proteins in sections of human conjunctival tissue obtained and used in accordance with the Declaration of Helsinki.
Results: :
Immunoreactive xGlu was detected in all epithelial cell layers of human bulbar/forniceal conjunctiva tissues. EAAT1 positive conjunctival cells were localized predominantly to the surface conjunctival epithelial cells. EAAT2 and EAAT3 positive epithelial cells were detected in the basal and surface cell layers, but absent from transitional epithelial cell layer of the conjunctiva. EAAT4 was detected in all epithelial cell layers of the conjunctiva, but was most pronounced in the epithelial cells along the conjunctival surface. All conjunctival epithelial cells were weakly positive for EAAT5. Also, immunoreactive Xc protein was expressed by all conjunctival epithelial cells, with highest levels in the epithelial cells at the surface of the bulbar/forniceal conjunctiva.
Conclusions: :
The expression of EAAT1-5 subtypes and Xc in GGT and GS positive epithelial cells containing xGlu in the basal, transitional and surface layers of the bulbar/forniceal conjunctiva supports active transport and metabolism of Glu/Gln in the conjunctiva.
Keywords: conjunctiva • differentiation • metabolism