Abstract
Purpose: :
Glaucomatous optic neuropathy is multifactorial in origin including immunological alteration. Here we examined the cell survival rates of retinal ganglion cells (RGCs) in several immunological conditions in response to ischemic insults.
Methods: :
Animal protocols were in accordance with ARVO/IACUC guidelines. Transient retinal ischemia model were generated in the right eyes of all animals tested. All left eyes served as control. Intraocular pressure of the right eyes was raised to create retinal ischemia for 1 hour. To evaluate the effects of lymphocyte T and B cells on RGC survival, we first examined the retinas from C57BL/6 control, SCID mice lacking T and B cells, and SCID mice which adoptively pre-transferred with an enriched CD4+T cell population obtained from splenocytes of C57BL/6 mice by flow cytometry after ischemia-reperfusion (I/R) injury. Eyes were harvested 21 days after induction of I/R and fluorescence dye Fluorogold was used to retrogradely label surviving RGCs. Cell survival was determined by counting labeled RGCs in the whole-mounted retinas. Using STAT4(–/–) and STAT6(–/–) mice we also evaluated the effects of TH (T helper) 1 or TH2 signaling on RGC survival in response to ischemic injury. All animals were terminated at 48 hours after I/R indult. The eyes were enucleated and processed for HE staining to counting the cells in ganglion cell layers.
Results: :
The numbers of surviving RGCs were strikingly declined in C57BL/6 eyes in response to ischemia (n=5, 78±4% of survival cells in contralateral control eyes), while in SCID mice, there was no differences between ischemic and control eyes (n=7, 93±5% of the survival cells in contralateral eye). The RGCs from the immunologically deficient animals showed significantly resistance to ischemic injury compared the RGCs from wild type controls (P<0.01). An adoptive transfer of CD4+T lymphocytes derived from C57BL/6 into SCID mice caused significantly loss of RGCs similar to C57BL/6. We further observed that the RGCs from STAT6(-/-) animals also showed significantly resistance to ischemic injury compared with the RGCs from C57BL/6 controls 48 hours after I/R insults (P<0.05). RGCs from STAT4(-/-) animals showed similar result as well as from C57BL/6.
Conclusions: :
Our results supported that the injury of RGCs in response to I/R is strongly associated with immunological functions.
Keywords: ganglion cells • immunomodulation/immunoregulation • signal transduction