Cross-linked Actin Networks (CLANs) were first identified in bovine trabecular meshwork (BTM) cells in response to steroid treatment. Since then, work within our group has identified CLANs in human TM (HTM) cells and human tissue ex vivo. An alteration in the cytoskeleton of TM cells has been associated with changes in outflow facility and is a promising therapeutic target in glaucoma research. CLANs which are believed to make TM cells more rigid, were found in increase numbers in tissue from glaucomatous donors, but were also present in tissue from non-glaucomatous donors. This would indicate that CLAN formation is not merely a steroid response but may be triggered by changes within the outflow system. The current work set out to identify CLAN inducing agents present within the normal outflow system and questioned whether age-related changes within the anterior chamber could influence CLAN number in a similar manner to glaucoma. Investigating the influence of aqueous humor (AH) and some of its constituent growth factors on CLAN formation in both BTM and HTM cells revealed that AH itself was capable of inducing CLANs and that the main CLAN inducing agent present was TGF-β2. Conversely mitogenic growth factors (FGF and HGF) did not increase CLAN incidence and implicated that CLAN incidence was linked to cell shape change linked and therefore to function. In vitro analysis of CLANs in reference to donor age revealed that TGF-β2 could induce a higher percentage of CLANs in HTM cells from older donors compared to HTM cells derived from younger donors. Ex vivo analysis run in parallel demonstrated that CLAN incidence increased with increasing donor age.In order to identify how age-related stress within the TM environment influenced CLAN incidence cells were treated with hydrogen peroxide. In BTM cells pre-treatment for 1 hour was sufficient to significantly increase CLAN incidence. In further experiments it would seem that CLANs are not associated with apoptotic cells nor with senescent cells. The findings of this study indicate that CLANs can form when no glaucomatous pathology is detected and that changes in the extracellular environment can influence their formation. This is especial evident in older tissue.
|Place of Publication||University of Liverpool|
|Publication status||Published - 1 May 2013|
- Trabecular Meshwork