Expression and distribution of matrix metalloproteinases and their inhibitors in the human iris and ciliary body

Abstract

Aim: To determine the expression and distribution of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) in the normal human iris and ciliary body. Methods: Seven postmortem human eyes were fixed with formalin. The iris and ciliary body were dissected out and embedded in paraffin. The expression of MMPs -1, 2, 3, and 9, and TIMPs 1-4 in the iris and ciliary body was determined by a novel immunofluorescence technique and the results graded by masked observers. Results: Positive staining for MMPs and TIMPs was observed in all regions of the anterior uvea, and was more intense in the ciliary body than in the iris. Most MMPs and TIMPs showed similar patterns in their distribution. In the ciliary body, staining was strongest in the epithelium, and was localised to the epithelial cell cytoplasm, except for TIMP-3 which was strongly expressed in the basement membranes. In the iris, staining was most noticeable in the anterior border and anterior epithelial layer. Blood vessels in the stroma of the iris and ciliary body also stained moderately for MMPs and TIMPs. Conclusion: Both MMPs and TIMPs are widely expressed in the anterior uvea, with a positive correlation between their expressions. Their differential localisation in the ciliary body suggests they may have a role in maintaining homeostasis in the uveal tract.

Plasma and aqueous humour levels of homocysteine in exfoliation syndrome

“…The authors suggest that complex changes in the local MMP-TIMP balance and reduced MMP activity in the aqueous humour may promote the abnormal matrix accumulation characteristic of XFS with evident implication in the pathogenesis of XFG. Both MMPs and TIMPs are widely expressed in the anterior uvea, and their differential localization in the ciliary body in particular suggests they may have a physiologic role in maintaining homeostasis in the uveal tract [19].…”

Physiological Significance and Expression of P450s in the Developing Eye

“…5). The ciliary body is considered as a primary source of aqueous humor generation and is involved in production of signal mediators modulating the extracelluar matrix turnover by secreting metalloproteases and is also involved in regulating IOP (Coca-Prados et al, 1999;Lan et al, 2003;Civan and Macknight, 2004). The conserved expression pattern of CYP1B1 orthologs in mouse and human eye, its absence in the trabecular meshwork (TM) region, but presence in the ICE, and possibly lens epithelium, in fetal and adult stages suggest a role in the development and regulation of the function of the TM; perhaps the Cyp1b1 acts to modify some endogenous substrate, necessary for normal TM development and function, that gets secreted into the aqueous humor (Fig.…”

Paediatric IOL implantation and postoperative refractive state: what role do study methodology and surgical technique play?

“…It is notable that this is a study in which every IOL was placed in the sulcus; in other studies, the IOL was implanted within the capsular bag,13 19–21 or the specific differentiation of in-the-bag versus sulcus fixation was not made 12 14–16 18. As the sulcus may correlate to the area of putative motor control of emmetropisation,10 11 does sulcus fixation for IOLs affect axial elongation? Thus, as uncomfortable as it is to contemplate, the surgical techniques involved in infant cataract surgery may be culpable.…”

“…It is speculated that the effector component is controlled by the ocular matrix metalloproteinases (MMPs) which orchestrate posterior segment remodelling 8. The primary site of this motor arm is unclear and may be located at the posterior pole,9 or the area around the ciliary body 10 11…”