Effect of Mechanical Stress on Nuclear Factor kappa B Activation in Trabecular Meshwork Cells

Abstract

Abstract: : Purpose: To investigate the effects of mechanical stretch onactivation of nuclear factor kappa B (NF-ΚB) by cytokines suchas interleukin-1α (IL-1α). NF-ΚB is thought to mediate the tissue-specificstress response that characterizes glaucomatous trabecular meshwork.Methods: Bovine and human trabecular meshwork (TM) cells (passage2-4) were grown on collagen-coated, flexible elastomer membranes.TM cells were subjected to 5-10% biaxial stretch for varioustime periods before or during exposure to IL-1α (0.5-10 ng/ml).The TM cells were assayed for NF-ΚB activation by immunofluorescencewith antibodies to NF-ΚB p65 subunit (RelA) or by electrophoreticmobility shift assay of nuclear extracts.Results: Both prolonged(>5 hours) mechanical stretching and IL-1α (2-10 ng/ml for1 hour) alone can induce activation of NF-ΚB in TM cells. WhenTM cells were exposed to mechanical stretching and IL-1α simultaneously,NF-ΚB translocation occurred sooner and more extensively comparedto either condition alone (left image, cells exposed to mechanicalstretch and IL-1α for 1 hour). However, when TM cells were subjectedto at least 1 hour of mechanical stretch prior to IL-1α exposure,activation of NF-ΚB was significantly inhibited (right image,cells exposed to 2 hours of mechanical stretch followed by 1hour of 10 ng/ml IL-1α). 

 

Conclusions: While simultaneousmechanical stretch can enhance activation of NF-ΚB by IL-1α, pre-treatmentof TM cells with mechanical stretch can block the activationof NF-ΚB by even high levels of IL-1α.

Keywords: outflow: trabecular meshwork • stress response • trabecular meshwork