Immunohistochemical analysis of extracellular matrix bleb capsules of functioning and non‐functioning glaucoma drainage implants

Abstract

ABSTRACT.Purpose: To detect by immunohistochemical means the changes in bleb capsules at the cellular level between functioning and non-functioning glaucoma drainage implants (GDIs). Methods: Three samples each of functioning (1 Baerveldt and 2 Molteno implants) and non-functioning filtration blebs (1 Molteno and 2 Ahmed implants) were studied. A non-functioning bleb was defined as an intra-ocular pressure (IOP) >21 mmHg or a <20% reduction in IOP from baseline on three consecutive follow-up visits with maximal tolerated medication. The capsules were obtained between 6 and 108 months after GDI insertion for medical reasons only. Primary antibodies were used to stain fibronectin, tenascin, laminin, collagen IV and smooth muscle actin (SMA). The samples were graded on the basis of the intensity and quantity of immunohistochemical staining into four categories as follows: no staining or a mild, moderate or marked staining. Results: The non-functioning blebs expressed more fibronectin, tenascin and SMA through the whole capsule wall than the functioning blebs. In the functioning blebs, tenascin was found mainly in the inner layer of the capsule. More type IV collagen and laminin were also found in the non-functioning bleb capsules than in the functioning blebs. No difference was found between the bleb capsules irrespective of whether they had been perfused with aqueous humour immediately after surgery (Ahmed) or after a delay (Molteno, Baerveldt). Conclusion: Accumulation of extracellular matrix components and activated fibroblasts in the bleb capsules of non-functioning GDI indicates the presence of an active wound healing process, suggesting a possible reduction in filtration through the bleb wall.

Risk factors for the hypertensive phase after implantation of a glaucoma drainage device

“…Immunohistochemical staining of bleb after AGV implantation showed α ‐smooth muscle actin‐positive myofibroblasts (Jung et al. ; Valimaki & Uusitalo ). McBrien & Gentle () reported an increase in α ‐smooth muscle actin in the sclera of three shrews with induced myopia, which is a key component of the cytoskeleton of myofibroblast cells.…”

Oxidized low‐density lipoprotein, lipid and calcium aggregates reveal oxidative stress and inflammation in the conjunctiva of glaucoma patients

“…Thus, it is possible that there is a connection between chronic inflammation, alterations in tissue remodelling (Helin‐Toiviainen et al. ; Välimäki & Uusitalo ) expression of extracellular matrix proteins (Välimäki & Uusitalo ) and lipid accumulation resembling a wound healing cascade similar to atherosclerotic plaque formation. These alterations may interfere with the normal wound healing process eventually influencing surgical outcome.…”

Complementary effects of bevacizumab and MMC in the improvement of surgical outcome after glaucoma filtration surgery

“…However, it is known that increased fibrosis may result from accumulation of extracellular matrix (ECM) structural proteins, such as matrix metalloproteinases (MMP), fibronectin and laminin. Therefore, as recently described, a detailed evaluation of ECM degradation by immunohistochemical stainings might indicate bleb failure and could be helpful to distinguish functioning from non-functioning blebs (Valimaki & Uusitalo 2014. One should also remain cautious with extrapolating of findings from animal research to the care of human disease, as it is known that animal models never form precise replicas of the human pathology.…”