Abstract
Purpose: :
The mechanical strain induced by increased intraocular pressure (IOP) can damage retinal cells, with inflammatory signals being key aspects of this response. While astrocytes have a role, we asked whether ganglion cells could themselves contribute. This study asked whether mechanical strain triggered a release of cytokines and chemokines directly from isolated retinal ganglion cells.
Methods: :
Isolated immunopanned retinal ganglion cells were grown on silicone substrates. Cells were stretched for 4 min at 4.1% strain followed by 1 min at 0% strain with the cycle repeated thrice over 15 min. Samples of extracellular solution were taken before and after stretch and levels of inflammatory mediators were determined using a rat antibody cytokine array. Lactose dehydrogenase (LDH) was determined by a colorimetric coupled reaction.
Results: :
Stretching isolated ganglion cells led to a significant increase in the extracellular levels of numerous cytokines and chemokines. The largest increase was found for IL-3 (1.6 fold), CXCL9 (1.5 fold), TNF-α (1.5 fold) and VEGF (1.4 fold; all p<0.001). IL-1β, IL-4, IL-6, CXCL7, L-selectin and LIX were also significantly higher in the bath after stretch (p<0.01). Extracellular levels of LDH were not changed after stretch, implying that the increase in cytokines and chemokines represented a physiological release.
Conclusions: :
This study demonstrates that isolated retinal ganglion cells can release various cytokines and chemokines upon application of mechanical strain. It should be noted that relative changes represent release from non-confluent neurons into a large bath area, and elevations in situ are expected to be substantially higher.
Keywords: intraocular pressure • ganglion cells • cytokines/chemokines