Matrix metalloproteinases and tissue inhibitors of metalloproteinases in the aqueous humour of patients with primary angle closure glaucoma - a quantitative study

Expression of Matrix Metalloproteinase-3 in the Aqueous Humor of Patients with Posner-Schlossman Syndrome

PURPOSE

To explore the expression of matrix metalloproteinase-3 (MMP-3) in the aqueous humor of patients with Posner-Schlossman syndrome (PSS), and the association between MMP-3 and PSS.

METHODS

Peripheral blood and aqueous humor were routinely collected from 29 patients with PSS (PSS group) and 30 patients with age-related-cataract (ARC) (control group). The content of MMP-3 in serum and aqueous humor was measured by immunoturbidimetry. The correlation between MMP-3 and ophthalmic examination results were verified by Spearman's correlation analysis.

RESULTS

The MMP-3 level in the aqueous humor of the PSS group was (25.86 ± 13.4)ng/ml, significantly higher than that in the control group (3.9 ± 2.7)ng/ml(p < 0.001), while there was no significant difference in serum MMP-3 level between the two groups (p = 0.125). The endothelial cell density (ECD) in the aqueous humor of the PSS group was (2078 ± 440) cell/mm2, intraocular pressure (IOP) in the aqueous humor of the PSS group was (33 ± 12) mmHg. The correlation analysis of aqueous humor MMP-3 and various ophthalmic examination results showed that aqueous humor MMP-3 had a moderate correlation with IOP and the difference in ECD between the affected eye and the fellow eye.

CONCLUSIONS

MMP-3 level is elevated in the aqueous humor of PSS patients, and it may play an important role in the pathogenesis of PSS.

Relative ability of aqueous humor from dogs with and without primary angle-closure glaucoma and ADAMTS10 open-angle glaucoma to catalyze or inhibit collagenolysis

OBJECTIVE

The objective of the study was to compare the ability of aqueous humor (AH) from dogs with primary angle-closure glaucoma (CPACG), companion dogs without overt evidence of CPACG, and Beagles with and without ADAMTS10 open-angle glaucoma (ADAMTS10-OAG) to catalyze or inhibit collagenolysis.

ANIMALS STUDIED

Seventeen normal pet dogs, 27 dogs with CPACG, 19 Beagles with ADAMTS10-OAG, and 4 unaffected Beagles.

PROCEDURES

A fluorescein-based substrate degradation assay was used to assess AH proteolytic capacity. Samples were then assayed using the same substrate degradation assay, with recombinant activated matrix metalloproteinase-2 (MMP-2) added to measure protease inhibition effects.

RESULTS

For the protease activity assay, relative fluorescence (RF) for AH from normal pet dogs was 13.28 ± 2.25% of control collagenase while RF for AH from dogs with CPACG was 17.47 ± 4.67%; RF was 8.57 ± 1.72% for ADAMTS10-OAG Beagles and 7.99 ± 1.15% for unaffected Beagles. For the MMP-2 inhibition assay, RF for AH from normal dogs was 34.96 ± 15.04% compared to MMP-2 controls, while RF from dogs with CPACG was 16.69 ± 7.95%; RF was 85.85 ± 13.23% for Beagles with ADAMTS10-OAG and 94.51 ± 8.36% for unaffected Beagles. Significant differences were found between dogs with CPACG and both normal pet dogs and dogs with ADAMTS10-OAG and between normal pet dogs and both groups of Beagles.

CONCLUSIONS

AH from dogs with CPACG is significantly more able to catalyze proteolysis and inhibit MMP-2 than AH from normal dogs or dogs with ADAMTS10-OAG. Results suggest that pathogenesis may differ between CPACG and ADAMTS10-OAG.

Pathogenesis of Common Ocular Diseases: Emerging Trends in Extracellular Matrix Remodeling

The prevalence of visual impairments in human societies is worrying due to retinopathy complications of several chronic diseases such as diabetes, cardiovascular diseases, and many more that are on the rise worldwide. Since the proper function of this organ plays a pivotal role in people's quality of life, identifying factors affecting the development/exacerbation of ocular diseases is of particular interest among ophthalmology researchers. The extracellular matrix (ECM) is a reticular, three-dimensional (3D) structure that determines the shape and dimensions of tissues in the body. The ECM remodeling/hemostasis is a critical process in both physiological and pathological conditions. It consists of ECM deposition, degradation, and decrease/increase in the ECM components. However, disregulation of this process and an imbalance between the synthesis and degradation of ECM components are associated with many pathological situations, including ocular disorders. Despite the impact of ECM alterations on the development of ocular diseases, there is not much research conducted in this regard. Therefore, a better understanding in this regard, can pave the way toward discovering plausible strategies to either prevent or treat eye disorders. In this review, we will discuss the importance of ECM changes as a sentimental factor in various ocular diseases based on the research done up to now.

MicroRNA-93 promotes the pathogenesis of glaucoma by inhibiting matrix metalloproteinases as well as up-regulating extracellular matrix and Rho/ROCK signaling pathways

Objective

To investigate the effect and potential molecular mechanism of microRNA-93 (miR-93) on retinal ganglion cells (RGCs) apoptosis as well as retinal damage in acute glaucoma mice.

Methods

RGCs apoptosis were induced by oxygen-glucose deprivation and reperfusion (OGD/R). The pro-apoptotic effect of miR-93 was evaluated by transfecting miR-93 mimics or miR-93 inhibitor into OGD/R-induced RGCs. The viability and apoptosis of RGCs were determined by MTT assay and flow cytometry. Mouse model of acute glaucoma were successfully induced via high intraocular pressure (IOP), and then these model animals were randomly divided into vehicle group, miR-93 mimics group or miR-93 inhibitor group (n = 10), using healthy mice as normal control. Histopathologic changes of retinal tissue were evaluated by Hematoxylin and Eosin (H&E) staining method. Moreover, cell counts of retinal ganglion cell layer and mean thickness of different layers were also determined. Quantitative real-time PCR (qPCR) and western blotting analysis were used to detect the mRNA and protein expression levels of extracellular matrix (ECM), matrix metalloproteinases (MMPs) and Rho/ROCK signaling pathway.

Results

miR-93 mimics significantly decreased or promoted the viability and apoptosis of OGD/R-induced RGCs, respectively. In addition, miR-93 mimics significantly exacerbated the degree of retinal tissue damage in mice with acute glaucoma, which was accompanied by a decrease in the number of ganglion cell layer (GCL) cells and the thickness of different tissue layers. Moreover, miR-93 mimics significantly increased IOP in mice with acute glaucoma. Significantly, miR-93 inhibitors significantly reversed the above changes. In addition, results of Western blot analysis showed that miR-93 mimics increased and decreased the expression of ECM-associated and MMP-associated proteins, respectively, by activating the Rho/ROCK signaling pathway. In contrast, miR-93 significantly decreased and increased the expression of ECM-associated and MMP-associated proteins, and suppressed the expression of Rho/ROCK signaling pathway-related proteins.

Conclusion

miR-93 can promote the development of glaucoma by activating Rho/ROCK signaling pathway to mediate the accumulation of ECM-related proteins as well as the down-regulation of MMP-related proteins.

Intracameral Injection of AAV-DJ.COMP-ANG1 Reduces the IOP of Mice by Reshaping the Trabecular Outflow Pathway

Purpose

The angiopoietin-1 (ANG1)-TIE signaling pathway orchestrates the development and maintenance of the Schlemm's canal (SC). In this study, we investigated the impact of adeno-associated virus (AAV)-mediated gene therapy with cartilage oligomeric matrix protein-ANG1 (COMP-ANG1) on trabecular outflow pathway.

Methods

Different serotypes of AAVs were compared for transduction specificity and efficiency in the anterior segment. The selected AAVs encoding COMP-ANG1 or ZsGreen1 (control) were delivered into the anterior chambers of wild-type C57BL/6J mice. The IOP and ocular surface were monitored regularly. Ocular perfusion was performed to measure the outflow facility and label flow patterns of the trabecular drainage pathway. Structural features of SC as well as limbal, retinal, and skin vessels were visualized by immunostaining. Ultrastructural changes in the SC and trabecular meshwork were observed under transmission electron microscopy.

Results

AAV-DJ could effectively infect the anterior segment. Intracameral injection of AAV-DJ.COMP-ANG1 lowered IOP in wild-type C57BL/6J mice. No signs of inflammation or angiogenesis were noticed. Four weeks after AAV injection, the conventional outflow facility and effective filtration area were increased significantly (P = 0.005 and P = 0.04, respectively). Consistently, the area of the SC was enlarged (P < 0.001) with increased density of giant vacuoles in the inner wall (P = 0.006). In addition, the SC endothelia lay on a more discontinuous basement membrane (P = 0.046) and a more porous juxtacanalicular tissue (P = 0.005) in the COMP-ANG1 group.

Conclusions

Intracamerally injected AAV-DJ.COMP-ANG1 offers a significant IOP-lowering effect by remodeling the trabecular outflow pathway of mouse eyes.

Endothelial Glycocalyx Morphology in Different Flow Regions of the Aqueous Outflow Pathway of Normal and Laser-Induced Glaucoma Monkey Eyes

Glycocalyx morphology was examined in the trabecular outflow pathway of monkey eyes with and without experimental glaucoma. Laser burns were administered along ~270 degrees of the trabecular meshwork (TM) of one eye (n = 6) or both eyes (n = 2) of each monkey until intraocular pressure remained elevated. Portions of the TM were not laser-treated. Unlasered eyes (n = 6) served as controls. Enucleated eyes were perfused at 15 mmHg to measure the outflow facility, perfused with fluorescein to evaluate the outflow pattern, perfusion-fixed for glycocalyx labeling, and processed for electron microscopy. Coverage and thickness of the glycocalyx were measured in the TM, Schlemm’s canal (SC), collector channels (CCs), intrascleral veins (ISVs), and episcleral veins (ESVs) in non-lasered regions and high- and low-flow regions of controls. Compared to controls, laser-treated eyes had decreased outflow facility (p = 0.02). Glycocalyx thickness increased from the TM to ESVs in non-lasered regions and controls (p < 0.05). Glycocalyx coverage was generally greater distally in non-lasered regions (p < 0.05). In lasered regions, TM, SC, and CCs were partly to completely obliterated, and ISVs and ESVs displayed minimal glycocalyx. Whether the glycocalyx is decreased in the trabecular outflow pathway of human glaucomatous eyes warrants investigation.

The Role of Metalloproteinases and Their Tissue Inhibitors on Ocular Diseases: Focusing on Potential Mechanisms

Eye diseases are associated with visual impairment, reduced quality of life, and may even lead to vision loss. The efficacy of available treatment of eye diseases is not satisfactory. The unique environment of the eye related to anatomical and physiological barriers and constraints limits the bioavailability of existing agents. In turn, complex ethiopathogenesis of ocular disorders that used drugs generally are non-disease specific and do not act causally. Therefore, there is a need for the development of a new therapeutic and preventive approach. It seems that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have a significant role in the development and progression of eye diseases and could be used in the therapy of these disorders as pharmacological targets. MMPs and TIMPs play an important role in the angiogenesis, epithelial-mesenchymal transition, cell invasion, and migration, which occur in ocular diseases. In this review, we aim to describe the participation of MMPs and TIMPs in the eye diseases, such as age-related macular degeneration, cataract, diabetic retinopathy, dry eye syndrome, glaucoma, and ocular cancers, posterior capsule opacification focusing on potential mechanisms.

Evaluation of matrix metalloproteinases and tissue inhibitors of metalloproteinases in aqueous humor of dogs with versus without naturally occurring primary angle-closure glaucoma

OBJECTIVE

To compare concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in aqueous humor from ophthalmologically normal dogs and dogs with naturally occurring primary angle-closure glaucoma (cPACG).

SAMPLE

Aqueous humor samples from 12 eyes with cPACG and 18 ophthalmologically normal eyes of dogs.

PROCEDURES

A multiplex fluorescence-based ELISA was used to measure concentrations of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-13, TIMP-1, TIMP-2, and TIMP-4. Results for eyes with versus without cPACG were compared.

RESULTS

Significantly higher mean concentrations of MMP-1 (45% higher), MMP-2 (55% higher), MMP-3 (39% higher), MMP-8 (79% higher), MMP-9 (29% higher), MMP-10 (60% higher), TIMP-1 (63% higher), and TIMP-2 (136% higher) were detected in aqueous humor from eyes with cPACG, compared with ophthalmologically normal eyes.

CLINICAL RELEVANCE

MMPs and TIMPs have pivotal roles in extracellular matrix turnover and homeostasis in the outflow pathways of the eye. Results of the present study documented higher concentrations of MMPs and TIMPs in aqueous humor samples from dog eyes with late-stage cPACG. Although, to our knowledge, TIMPs have not previously been evaluated in the context of cPACG, the markedly higher concentration of TIMPs in eyes with cPACG suggested that inhibition of proteolysis and extracellular matrix turnover might be a factor in the development of glaucoma in susceptible individuals. However, because the present study used samples from dogs with late-stage cPACG, further work is required to characterize the temporal relationship between MMP and TIMP concentration changes and onset or progression of disease.

Different grinding speeds affect induced regeneration capacity of human treated dentin matrix

Human-treated dentin matrix (hTDM) is a biomaterial scaffold, which can induce implant cells to differentiate into odontoblasts and then form neo-dentin. However, hTDM with long storage or prepared by high-speed handpiece would not to form neo-dentin. In this research, we developed two fresh hTDM with different grinding speeds, which were low-speed hTDM (LTDM) with maximum speed of 500 rpm and high-speed hTDM (HTDM) with a speed of 3,80,000 rpm. Here, we aim to understand whether there were induced regeneration capacity differences between LTDM and HTDM. Scanning electron microscope showed that DFCs grew well on both materials, but the morphology of DFCs and the extracellular matrix was different. Especially, the secreted extracellular matrixes on the inner surface of LTDM were regular morphology and ordered arrangement around the dentin tubules. The transcription-quantitative polymerase chain reaction (qRT-PCR), western blot and immunofluorescence assay showed that the dentin markers DSPP and DMP-1 were about 2× greater in DFCs induced by LTDM than by HTDM, and osteogenic marker BSP was about 2× greater in DFCs induced by HTDM than by LTDM. Histological examinations of the harvested grafts observed the formation of neo-tissue were different, and there were neo-dentin formed on the inner surface of LTDM and neo-cementum formed on the outer surface of HTDM. In summary, it found that the induction abilities of LTDM and HTDM are different, and the dentin matrix is directional. This study lays a necessary foundation for searching the key factors of dentin regeneration in future.

Sodium 4-Phenylbutyrate Reduces Ocular Hypertension by Degrading Extracellular Matrix Deposition via Activation of MMP9

Ocular hypertension (OHT) is a serious adverse effect of the widely prescribed glucocorticoid (GC) therapy and, if left undiagnosed, it can lead to glaucoma and complete blindness. Previously, we have shown that the small chemical chaperone, sodium-4-phenylbutyrate (PBA), rescues GC-induced OHT by reducing ocular endoplasmic reticulum (ER) stress. However, the exact mechanism of how PBA rescues GC-induced OHT is not completely understood. The trabecular meshwork (TM) is a filter-like specialized contractile tissue consisting of TM cells embedded within extracellular matrix (ECM) that controls intraocular pressure (IOP) by constantly regulating aqueous humor (AH) outflow. Induction of abnormal ECM deposition in TM is a hallmark of GC-induced OHT. Here, we investigated whether PBA reduces GC-induced OHT by degrading abnormal ECM deposition in TM using mouse model of GC-induced OHT, ex vivo cultured human TM tissues and primary human TM cells. We show that topical ocular eye drops of PBA (1%) significantly lowers elevated IOP in mouse model of GC-induced OHT. Importantly, PBA prevents synthesis and deposition of GC-induced ECM in TM. We report for the first time that PBA can degrade existing abnormal ECM in normal human TM cells/tissues by inducing matrix metalloproteinase (MMP)9 expression and activity. Furthermore, inhibition of MMPs activity by chemical-inhibitor (minocycline) abrogated PBA's effect on ECM reduction and its associated ER stress. Our study indicates a non-chaperone activity of PBA via activation of MMP9 that degrades abnormal ECM accumulation in TM.

Hyperbranched Cationic Glycogen Derivative-Mediated IκBα Gene Silencing Regulates the Uveoscleral Outflow Pathway in Rats

The role of the IκB/NF-κB signaling pathway in the uveoscleral outflow pathway was investigated with IκBα gene silencing mediated by the 3-(dimethylamino)-1-propylamine-conjugated glycogen (DMAPA-Glyp) derivative. The IκBα-siRNA-loaded DMAPA-Glyp complex was transfected into the ciliary muscles of rats by intracameral injection (labeled as the DMAPA-Glyp+siRNA group). The Lipofectamine™ 2000 (Lipo)/siRNA complex and the naked siRNA were set as the controls. The mRNA and protein expression of IκBα, NF-κBp65, and MMP-2 were analyzed by real-time PCR, western blotting, and in situ gelatin zymography. Nuclear translocation of NF-κBp65 was analyzed by immunofluorescence. Rat intraocular pressure (IOP) was monitored pre- and postinjection. Gene transfection efficiency and toxicity of the DMAPA-Glyp derivative were also evaluated. After RNA interference (RNAi), IκBα mRNA and protein expression were significantly inhibited. NF-κBp65 mRNA and protein expression showed no significant differences. Nevertheless, nuclear translocation of NF-κBp65 occurred in the DMAPA-Glyp+siRNA group. Both mRNA expression and activity of MMP-2 increased, with the largest increase in the DMAPA-Glyp+siRNA group. IOP in the DMAPA-Glyp+siRNA group fell to the lowest level on day 3 after RNAi. The levels of Cy3-siRNA in the ciliary muscle of the DMAPA-Glyp+siRNA group did not significantly decrease over time. At 7 and 14 d after RNAi, no significant pathological damage was detectable in the eyes injected with the DMAPA-Glyp derivative or the DMAPA-Glyp/siRNA complex. Taken together, our results suggest that downregulation of IκBα expression in the ciliary muscle plays a crucial role in reducing the IOP values of rats. IκBα may become a new molecular target for lowering IOP in glaucoma. The DMAPA-Glyp derivative is safe and feasible as an effective siRNA vector in rat eyes.

Neuroinflammation in Primary Open-Angle Glaucoma

Primary open-angle glaucoma (POAG) is the second leading cause of irreversible blindness worldwide. Increasing evidence suggests oxidative damage and immune response defects are key factors contributing to glaucoma onset. Indeed, both the failure of the trabecular meshwork tissue in the conventional outflow pathway and the neuroinflammation process, which drives the neurodegeneration, seem to be linked to the age-related over-production of free radicals (i.e., mitochondrial dysfunction) and to oxidative stress-linked immunostimulatory signaling. Several previous studies have described a wide range of oxidative stress-related makers which are found in glaucomatous patients, including low levels of antioxidant defences, dysfunction/activation of glial cells, the activation of the NF-κB pathway and the up-regulation of pro-inflammatory cytokines, and so on. However, the intraocular pressure is still currently the only risk factor modifiable by medication or glaucoma surgery. This present review aims to summarize the multiple cellular processes, which promote different risk factors in glaucoma including aging, oxidative stress, trabecular meshwork defects, glial activation response, neurodegenerative insults, and the altered regulation of immune response.

[The role of metalloproteinases in the development of primary open-angle glaucoma]

The article reviews literature on the role of matrix metalloproteinases (MMP) in the development of eye pathologies, specifically primary open-angle glaucoma (POAG). Regulation of the extracellular matrix is carried out by proteolytic enzymes - metalloproteinases in particular - as well as specific inhibitors of their activity (tissue metalloproteinases inhibitors). The review also reveals its involvement in the pathogenesis of various types of glaucoma, decrease in stability of the intraocular liquid outflow, proves the role of MMR in the ganglionic apoptosis, remodeling of the optic disk and change of lamina cribrosa in primary open-angle glaucoma. There is research devoted to studying the interrelations of MMP genes with POAG development. Associations of single nucleotide polymorphic loci of MMP-1, MMP-2, MMP-9 genes with POAG are shown.

In Vitro Screening and Transfection Concentration Optimization of Cynomolgus Monkey IκBα-siRNA

Purpose

To seek for a small interfering RNA (siRNA) sequence targeting a cynomolgus monkey inhibitor of nuclear factor kappa B α (IκBα) that can specifically and effectively suppress IκBα gene expression of cynomolgus monkey ciliary muscle (CM) cells and trabecular meshwork (TM) cells in vitro and screen for optimal siRNA transfection concentration.

Methods

Three IκBα-specific double-stranded siRNAs were designed and synthesized. They were transfected into primarily cultured cynomolgus monkey CM cells and TM cells. The mRNA and protein levels of IκBα were examined by using real-time quantitative polymerase chain reaction (real-time PCR) and western blot to screen a pair of candidate valid sequences with the highest inhibitory rate. Both cells were transfected with Cy5-labeled nonspecific control-siRNA (NC-siRNA) of four different concentrations (10, 20, 50, and 100 nmol/L(nM)), and flow cytometry was used to assess transfection efficiency. Then, cells were transfected with the candidate valid IκBα -siRNA of the same four concentrations, and the cytotoxicity was detected by using Cell Counting Kit-8 (CCK8), and the inhibitory efficiency of IκBα was identified via real-time PCR to find out optimal siRNA transfection concentration.

Results

The suppression effect of the siRNA targeting the GCACTTAGCCTCTATCCAT of IκBα gene was most obvious by in vitro screening. The inhibitory rate of IκBα was 82% for CM cells and 82% for TM cells on the mRNA level and 98% for CM cells and 93% for TM cells on the protein level, respectively. The results of flow cytometry showed that the transfection efficiency was the highest at 100 nM, which was 89.0% for CM cells and 48.2% for TM cells, respectively. The results of CCK8 showed that there was no statistically significant difference in cell viability after transfection of different concentrations of IκBα-siRNA. The results of real-time PCR indicated that there was no statistical difference in the inhibitory efficiency of IκBα after transfection of different concentrations of IκBα-siRNA.

Conclusion

It proves that the siRNA targeting the GCACTTAGCCTCTATCCAT of IκBα gene is the valid sequence to suppress cynomolgus monkey IκBα expression of CM cells and TM cells by RNAi. 10 nM is the optimal transfection concentration.

Imbalance of Matrix Metalloproteinases and Their Inhibitors Is Correlated With Trabeculectomy Outcomes in Acute Primary Angle Closure

PURPOSE

To analyze matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs), and their molar ratios in the aqueous humor in previous acute primary angle closure (APAC) patients and their correlations with trabeculectomy outcomes.

DESIGN

Prospective cohort study.

METHODS

Aqueous humor samples were collected from a total of 78 eyes, including 52 previous APAC eyes and 26 cataract eyes. TIMP-1, 2, 3, and 4 and MMP-1, 2, 3, 7, 8, 9, 12, and 13 analyte concentrations were measured using multiplexed immunoassay kits. Patient follow-up occurred at 1 week and 1, 3, 6, 12, and 18 months.

RESULTS

In the previous APAC group, 11 MMP/TIMP molar ratios were significantly lower. APAC eyes were then followed for up to 18 months after trabeculectomy and divided into success (37 eyes) and failure (15 eyes) groups. Five out of the 11 molar ratios were significantly lower in the failure group than in the success group. In multiple logistic regression analysis, failed filtration surgery was more likely in APAC eyes with lower MMP-2/TIMP-2 (P = .040, odds ratio = 44.499) and MMP-13/TIMP-1 (P = .034, odds ratio = 37.947) ratios. Previous APAC eyes were divided according to MMP-2/TIMP-2 and MMP-13/TIMP-1 ratios. Compared to eyes with high ratios, eyes with low MMP-2/TIMP-2 and MMP-13/TIMP-1 ratios had significantly higher failure rates.

CONCLUSIONS

In previous APAC eyes, changes in MMP and TIMP levels resulted in MMP and TIMP imbalance. Lower MMP-2/TIMP-2 and MMP-13/TIMP-1 ratios in aqueous humor are risk factors for trabeculectomy failure. Modulating specific MMP/TIMP ratios may have potential clinical applications for filtration surgery.

Lowered Decorin With Aberrant Extracellular Matrix Remodeling in Aqueous Humor and Tenon's Tissue From Primary Glaucoma Patients

Purpose

To evaluate the inflammatory cytokine, growth factors, extracellular matrix (ECM) remodeling genes, profibrotic and antifibrotic molecules in patients undergoing glaucoma filtration surgery (GFS). Additionally, the effect of preoperative antiglaucoma medications (AGMs) and postoperative bleb status were related to these parameters.

Methods

Tenon's tissue and aqueous humour (AH) were collected from 207 patients undergoing GFS with primary open-angle glaucoma (POAG) (n = 77), primary angle-closure glaucoma (PACG) (n = 62), and cataract controls (n = 68). Monocyte chemoattractant protein-1 (MCP-1), connective tissue growth factor (CTGF), transforming growth factor β1/2 (TGF-β1/2), lysyl oxidase (LOX), lysyl oxidase L2 (LOXL2), elastin (ELN), collagen type 1 α 1 (COL1A1), secreted protein acidic and rich in cysteine (SPARC), α-smooth muscle actin (α-SMA), and decorin (DCN) were determined in tenon's tissue by real-time PCR and in AH using ELISA.

Results

A significant increase was observed in the transcripts of MCP-1, TGF-β2, and SPARC in POAG and PACG (P < 0.05); CTGF, TGF-β1, LOX, LOXL2, ELN, COL1A1, and α-SMA in PACG (P < 0.05) compared with control. DCN transcript was significantly decreased in POAG and PACG (P < 0.05) compared with control. The protein levels of CTGF, TGF-β1/β2, ELN, SPARC, and LOXL2 was significantly elevated in POAG and PACG (P < 0.05); DCN was decreased (P < 0.05) compared with control. These parameters showed significant association with duration of preoperative AGMs and postoperative bleb status.

Conclusions

This study demonstrates increased expression of growth factors and ECM molecules, both at protein and transcript levels in GFS patients. A decreased DCN in AH seems striking, and if restored might have a therapeutic role in minimizing postoperative scarring to improve GFS outcome.

Alteration of MCP-1 and MMP-9 in Aqueous Humor Is Associated with Secondary Glaucoma in Fuchs Uveitis Syndrome

PURPOSE

To analyze changes in concentrations of pro- or anti-inflammatory cytokines, chemokines, or metalloproteinases (MMP) in the aqueous humor (AH) in Fuchs uveitis syndrome (FUS) patients with (FUSwG) or without (FUSwoG) secondary glaucoma.

METHODS

AH samples were collected from 43 eyes of Caucasian subjects (FUSwoG: n = 11; FUSwG: n = 8; control eyes: n = 24). Concentrations of IL-8, MCP-1, MMP-1,-2,-3,-9, SAA, TGFß-1,-2,-3, and TNF-α were measured by multiplex bead assay analysis.

RESULTS

Compared with the control group, levels of IL-8, MCP-1, MMP-3, and MMP-9 in the AH were significantly increased in FUSwG and FUSwoG patients. In contrast to FUSwoG patients, MCP-1 and MMP-9 level were lower in FUSwG, while expression of MMP-2, MMP-3, and TGFβ-1 was increased.

CONCLUSION

In our experiments, glaucoma in FUS patients was associated with low levels of MCP-1 and MMP-9 in the AH, while expression of MMP-2, MMP-3, and TGFβ-1 increased. The alteration in these molecular patterns may contribute to the development of glaucoma in FUS.

Expression of matrix Metalloproteinases-2 and aquaporin-1 in corneoscleral junction after angle-closure in rabbits

Background

To investigate the expression of Matrix Metalloproteinases 2 and aquaporin-1 in corneoscleral junction and explore the mechanism of trabecular damageafter angle-closure.

Methods

Thirty New Zealand white rabbits were randomly assigned into 2 groups, theexperimental group (Group 1) including twenty five rabbits and the control group (Group 2) including 5 rabbits. The rabbits in the experimental group were used to establish angle-closure models, and the rabbits in the control group were not subjected to any operation. All the rabbits were followed by slit lamp microscopy, Tonopen tonometer, and anterior segment optical coherent tomography (AS-OCT). The expressions of metalloproteinase MMP-2, aquaporin-1, and tissue inhibitors of metalloproteinase-2 in corneoscleral junctionwere evaluatedin both groups byimmunofluorescence, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and enzyme-linked immunosorbent assay (ELISA).

Results

Slit-lamp examination showed that angle-closure model was successfully established in twenty rabbits. The extent of angle-closure was about 2 to 4 clock hours in all the rabbit models, but the intraocular pressure (IOP) of the rabbits distributed from 8.57 to 15.25 mmHg and no significant high IOP was found in the follow-up period. The AQP-1-positive cells mainly located in Schlemm’s canal, the inner surface of trabecular meshwork (TM), and the surface of iris, which began to decline on 1 month after angle-closure. MMP2 staining was diffuse in trabecular meshwork and iris. Immunofluorescence signal of MMP2 was strong within 1 month after angle-closure, and subsequently became weak. qRT-PCR and ELISA showed that the expression of MMP-2 and TIMP-2 increased within 1 month after angle-closure and then declined gradually. The AQP-1 levels showed slightly declined on 1 month after angle-closure.

Conclusions

Altered levels of MMPs, TIMPs, and AQP-1 were found in the area of angle-closure, which may be involved in the damage of TM and Schlemm’s canal after angle-closure.

Trabecular meshwork ECM remodeling in glaucoma: could RAS be a target?

INTRODUCTION

Disturbances of extracellular matrix (ECM) homeostasis in trabecular meshwork (TM) cause increased aqueous outflow resistance leading to elevated intraocular pressure (IOP) in glaucomatous eyes. Therefore, restoration of ECM homeostasis is a rational approach to prevent disease progression. Since renin-angiotensin system (RAS) inhibition positively alters ECM homeostasis in cardiovascular pathologies involving pressure and volume overload, it is likely that RAS inhibitors reduce IOP primarily by restoring ECM homeostasis. Areas covered: Current evidence showing the presence of RAS components in ocular tissue and its role in regulating aqueous humor dynamics is briefly summarized. The role of RAS in ECM remodeling is discussed both in terms of its effects on ECM synthesis and its breakdown. The mechanisms of ECM remodeling involving interactions of RAS with transforming growth factor-β, Wnt/β-catenin signaling, bone morphogenic proteins, connective tissue growth factor, and matrix metalloproteinases in ocular tissue are discussed. Expert opinion: Current literature strongly indicates a significant role of RAS in ECM remodeling in TM of hypertensive eyes. Hence, IOP-lowering effect of RAS inhibitors may primarily be attributed to restoration of ECM homeostasis in aqueous outflow pathways rather than its vascular effects. However, the mechanistic targets for RAS inhibitors have much wider distribution and consequences, which remain relatively unexplored in TM.

Myocilin Regulates Metalloprotease 2 Activity Through Interaction With TIMP3

Purpose

To elucidate functions of wild-type myocilin, a secreted glycoprotein associated with glaucoma.

Methods

Lysates of mouse eyes were used for immunoprecipitation with affinity-purified antibodies against mouse myocilin. Shotgun proteomic analysis was used for the identification of proteins interacting with myocilin. Colocalization of myocilin and tissue inhibitor of metalloproteinases 3 (TIMP3) in different eye structures was investigated by a multiplex fluorescent in situ hybridization and immunofluorescent labeling with subsequent confocal microscopy. Matrix metalloproteinase 2 (MMP2) activity assay was used to test effects of myocilin on TIMP3 inhibitory action.

Results

TIMP3 was identified by a shotgun proteomic analysis as a protein that was coimmunoprecipitated with myocilin from eye lysates of wild-type and transgenic mice expressing elevated levels of mouse myocilin but not from lysates of transgenic mice expressing mutated mouse myocilin. Interaction of myocilin and TIMP3 was confirmed by coimmunoprecipitation of myocilin and TIMP3 from HEK293 cells transiently transfected with cDNAs encoding these proteins. The olfactomedin domain of myocilin is essential for interaction with TIMP3. In the eye, the main sites of myocilin and TIMP3 colocalization are the trabecular meshwork, sclera, and choroid. Using purified proteins, it has been shown that myocilin markedly enhanced the inhibitory activity of TIMP3 toward MMP2.

Conclusions

Myocilin may serve as a modulator of TIMP3 activity via interactions with the myocilin olfactomedin domain. Our data imply that in the case of MYOCILIN null or some glaucoma-causing mutations, inhibitory activity of TIMP3 toward MMP2 might be reduced, mimicking deleterious mutations in the TIMP3 gene.

Therapeutic potential of AAV-mediated MMP-3 secretion from corneal endothelium in treating glaucoma

Intraocular pressure (IOP) is maintained as a result of the balance between production of aqueous humour (AH) by the ciliary processes and hydrodynamic resistance to its outflow through the conventional outflow pathway comprising the trabecular meshwork (TM) and Schlemm's canal (SC). Elevated IOP, which can be caused by increased resistance to AH outflow, is a major risk factor for open-angle glaucoma. Matrix metalloproteinases (MMPs) contribute to conventional aqueous outflow homeostasis in their capacity to remodel extracellular matrices, which has a direct impact on aqueous outflow resistance and IOP. We observed decreased MMP-3 activity in human glaucomatous AH compared to age-matched normotensive control AH. Treatment with glaucomatous AH resulted in significantly increased transendothelial resistance of SC endothelial and TM cell monolayers and reduced monolayer permeability when compared to control AH, or supplemented treatment with exogenous MMP-3.Intracameral inoculation of AAV-2/9 containing a CMV-driven MMP-3 gene (AAV-MMP-3) into wild type mice resulted in efficient transduction of corneal endothelium and an increase in aqueous concentration and activity of MMP-3. Most importantly, AAV-mediated expression of MMP-3 increased outflow facility and decreased IOP, and controlled expression using an inducible promoter activated by topical administration of doxycycline achieved the same effect. Ultrastructural analysis of MMP-3 treated matrices by transmission electron microscopy revealed remodelling and degradation of core extracellular matrix components. These results indicate that periodic induction, via use of an eye drop, of AAV-mediated secretion of MMP-3 into AH could have therapeutic potential for those cases of glaucoma that are sub-optimally responsive to conventional pressure-reducing medications.

Associations between matrix metalloproteinase gene polymorphisms and glaucoma susceptibility: a meta-analysis

Background

Matrix metalloproteinases (MMPs) polymorphisms have been implicated in the pathogenesis of glaucoma risk. However, the results were controversial. We performed a meta-analysis to evaluate the precise associations between MMPs polymorphisms and glaucoma risk.

Methods

Related studies were reviewed by searching electronic databases within four databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association between the most common polymorphisms of MMPs and glaucoma risk. Heterogeneity, publication bias and sensitivity analysis were conducted to guarantee the statistical power.

Results

Overall, 11 selected articles involving 2,388 cases and 2,319 controls were included in this meta-analysis. Significant associations were only found between MMP-9 rs17576 G > A polymorphism (GA vs. GG: OR = 0.80, 95%CI = 0.67-0.97, P = 0.02, I² = 0%), MMP-9 rs3918249 C > T polymorphism (TT vs. CC + CT: OR = 0.71, 95%CI = 0.51-0.98, P = 0.04, I² = 0%) and glaucoma risk in the general population. Subgroup analysis also suggested that MMP-9 rs17576 G > A was related to glaucoma in the Caucasian population (GA vs. GG: OR = 0.67, 95%CI = 0.45-1.00, P = 0.05; GA + AA vs. GG: OR = 0.66, 95%CI = 0.45-0.97, P = 0.03, I² = 0%).

Conclusions

Our meta-analysis demonstrates that MMP-9 rs17576 G > A polymorphism might be a protective factor against the development of glaucoma in Caucasian population.

The SPARC-related modular calcium binding protein 2 (SMOC2) gene polymorphism in primary glaucoma: a case-control study

Primary glaucomas are among the most common eye diseases that may potentially result in bilateral blindness. Both genetics and environmental factors are reported to be involved in the etiology of primary glaucomas. Secreted protein acidic and rich in cysteine (SPARC)-related modular calcium binding protein 2 (SMOC2) is a matricellular glycoprotein encoded by the SMOC2 gene and known to regulate the expression of extracellular matrix (ECM) proteins and matrix metalloproteinases (MMPs), which play an important role in the pathogenesis of primary glaucomas. The frequencies of alleles and genotypes of SMOC2 variants were examined in 406 Saudi subjects, including primary open angle glaucoma (POAG, n=140) and primary angle closure glaucoma (PACG, n=64) patients and 202 matched healthy controls using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Genotyping of SMOC2 polymorphism (rs13208776) revealed a significantly higher frequency of the heterozygous genotype GA (P<0.01) and a lower frequency of wild type GG genotype (P=0.05) in glaucoma patients compared to the controls. Upon stratification of the patients on the basis of types of glaucoma, PACG patients had a significantly higher frequency of GA genotype as compared to the controls (P<0.01), whereas there was no significant difference between the POAG patient and control groups in frequencies of SMOC2 alleles and genotypes. Further, there was no significant difference in frequency distribution of alleles and genotypes between male and female patients. This study indicates that the GA genotype of SMOC2 (G>A) polymorphism is significantly associated with PACG and may be a risk factor. However, further large-scale studies in the Saudi population as well as in other ethnic populations are needed to confirm this association.

Correlations between Preoperative Angle Parameters and Postoperative Unpredicted Refractive Errors after Cataract Surgery in Open Angle Glaucoma (AOD 500)

PURPOSE

To assess the accuracy of intraocular lens (IOL) power prediction for cataract surgery with open angle glaucoma (OAG) and to identify preoperative angle parameters correlated with postoperative unpredicted refractive errors.

MATERIALS AND METHODS

This study comprised 45 eyes from 45 OAG subjects and 63 eyes from 63 non-glaucomatous cataract subjects (controls). We investigated differences in preoperative predicted refractive errors and postoperative refractive errors for each group. Preoperative predicted refractive errors were obtained by biometry (IOL-master) and compared to postoperative refractive errors measured by auto-refractometer 2 months postoperatively. Anterior angle parameters were determined using swept source optical coherence tomography. We investigated correlations between preoperative angle parameters [angle open distance (AOD); trabecular iris surface area (TISA); angle recess area (ARA); trabecular iris angle (TIA)] and postoperative unpredicted refractive errors.

RESULTS

In patients with OAG, significant differences were noted between preoperative predicted and postoperative real refractive errors, with more myopia than predicted. No significant differences were recorded in controls. Angle parameters (AOD, ARA, TISA, and TIA) at the superior and inferior quadrant were significantly correlated with differences between predicted and postoperative refractive errors in OAG patients (-0.321 to -0.408, p<0.05). Superior quadrant AOD 500 was significantly correlated with postoperative refractive differences in multivariate linear regression analysis (β=-2.925, R²=0.404).

CONCLUSION

Clinically unpredicted refractive errors after cataract surgery were more common in OAG than in controls. Certain preoperative angle parameters, especially AOD 500 at the superior quadrant, were significantly correlated with these unpredicted errors.