Abstract
Purpose: :
L-PGDS is a protein present in the cerebrospinal fluid (CSF). Recently, it has been reported that a marked concentration gradient of L-PGDS exists between the spinal CSF and the CSF in the subarachnoid space of the optic nerves in patients with papilledema in the setting of idiopathic intracranial hypertension (IIH) and in patients with normal-tension glaucoma (NTG). This paper analyzes the effect of various concentrations of L-PGDS (betatrace protein) on astrocyte proliferation and on mitochondrial production of ATP in cultured astrocytes.
Methods: :
Astrocytes (cell line LN 229) were cultured in Quantum 263 medium and then incubated with increasing concentrations of L-PGDS. Cell number and volume were analyzed with a CASY1 cell analyzer system. ATP production was measured using luminescence.
Results: :
Incubation of astrocytes with L-PGDS for 72 hours resulted in an inhibition of cellular proliferation that was correlated with an increased concentration of L-PGDS with a maximum inhibitory effect at 140µg/ml. Specifically, treatment of astrocytes with L-PGDS at a dose of 14µg/ml resulted in a decrease in cell number (73,573+18,600) compared with controls (135,970+52,480, p<0.005), with the cell numbers being even more decreased with increasing concentrations of L-PGDS at 70µg/ml and 140µg/ml. In our cultures, L-PGDS produced its maximal inhibiting effect at a dose of 140µg/ml, resulting in a cell number of 21,890+7110 (p<0.005), decreased six-fold compared with controls.Cells incubated with L-PGDS for 2 days showed significantly reduced ATP production compared with cells incubated with L-PGDS for 1 day (p<0.05) (Fig. 3). The effect of L-PGDS and incubation time on ATP production was highly significant (P=0.002, P<0.001, respectively).
Conclusions: :
L-PGDS inhibits astrocyte proliferation and astrocyte mitochondrial ATP production as a function of increasing L-PGDS concentration. This is the first study to show this specific effect. As the CSF is in contact with axons and mitochondria of the optic nerve, a change in the concentration of CSF proteins such as L-PGDS could exercise a harmful effect on these structures.1