Genetic association of -1562C>T polymorphism in the MMP9 gene with primary glaucoma in a north Indian population

Matrix Metalloproteinases and Glaucoma

Matrix metalloproteinases (MMPs) are enzymes that decompose extracellular matrix (ECM) proteins. MMPs are thought to play important roles in cellular processes, such as cell proliferation, differentiation, angiogenesis, migration, apoptosis, and host defense. MMPs are distributed in almost all intraocular tissues and are involved in physiological and pathological mechanisms of the eye. MMPs are also associated with glaucoma, a progressive neurodegenerative disease of the eyes. MMP activity affects intraocular pressure control and apoptosis of retinal ganglion cells, which are the pathological mechanisms of glaucoma. It also affects the risk of glaucoma development based on genetic pleomorphism. In addition, MMPs may affect the treatment outcomes of glaucoma, including the success rate of surgical treatment and side effects on the ocular surface due to glaucoma medications. This review discusses the various relationships between MMP and glaucoma.

Functionally significant polymorphisms of the MMP9 gene are associated with primary open-angle glaucoma in the population of Russia

PURPOSE

The aim of this study was to investigate the role of functionally significant loci of the matrix metalloproteinases genes 1, 3, 9 (MMP1, MMP3, and MMP9) in the development of primary open-angle glaucoma (POAG) in Caucasians of the Central region of Russia.

METHODS

In total 604 participants were recruited for the study, including 208 patients with POAG and 396 healthy controls. They were genotyped at eight single nucleotide polymorphisms (SNPs) of the three MMP genes. The association was analyzed using logistic and log-linear regression. POAG-associated loci and their proxies were in silico assessed for their functional prediction.

RESULTS

Variant allele G*rs2250889 of MMP9 was significantly associated with higher risk of POAG (OR_cov = 1.57-1.71). Haplotype CCA [rs3918242-rs3918249-rs17576] of the MMP9 gene was associated with lower risk of POAG (OR_cov = 0.33). Allele А*rs3787268 of MMP9 was associated with the low intraocular pressure in the POAG patients (β_cov = -0.176 - -0.272), and so were haplotypes AA [rs17576-rs3787268] (β_cov = -0.577) and AAC [rs17576-rs3787268- rs2250889] (β_cov = -0.742) of the same gene, whereas allele 2G*rs1799750 of MMP1 was associated with the earlier onset of the disease (β_cov = -0.112 - -0.218). In silico analysis of the polymorphisms suggested the functionality of POAG-associated SNPs and their proxies (epigenetic potential, expression and alternative splicing effects for several genes).

CONCLUSIONS

The MMP9 gene polymorphisms are associated with POAG and intraocular pressure in POAG patients; rs1799750 of MMP1 was associated with the earlier age of manifestation of the disease symptoms.

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.

Updates on Genes and Genetic Mechanisms Implicated in Primary Angle-Closure Glaucoma

Primary angle-closure glaucoma (PACG) is estimated to affect over 30 million people worldwide by 2040 and is highly prevalent in the Asian population. PACG is more severe and carries three times the higher risk of blindness than primary open-angle glaucoma, thus representing a significant public health concern. High heritability and ethnic-specific predisposition to PACG suggest the involvement of genetic factors in disease development. In the recent past, genetic studies have led to the successful identification of several genes and loci associated with PACG across different ethnicities. The precise cellular and molecular roles of these multiple loci in the development and progression of PACG remains to be elucidated. Nonetheless, these studies have significantly increased our understanding of the emerging cellular processes and biological pathways that might provide more significant insights into the disease’s genetic etiology and may be valuable for future clinical applications. This review aims to summarize and update the current knowledge of PACG genetics analysis research.

Dataset of allele and genotype frequencies of the three functionally significant polymorphisms of the MMP genes in Russian patients with primary open-angle glaucoma, essential hypertension and peptic ulcer

Data on the allele and genotype frequencies of the three functionally significant single nucleotide polymorphisms (SNPs) of the matrix metalloproteinases (MMP) genes (rs1799750 MMP1, rs3918242 and rs17576 MMP9) in Russian patients with primary open-angle glaucoma (POAG), essential hypertension (EH) and peptic ulcer (PU) are presented. Association studies identified these SNPs as possible significant markers associated with many multifactorial disorders, including POAG, EH, and PU. The frequencies of alleles and genotypes of the three SNPs in Russian patients with POAG, EH, and PU were presented separately for the entire study sample, females, and males, respectively. The data can be used as a reference for the Russian population.

Role of matrix metalloproteinase-9 gene polymorphisms in glaucoma: A hospital-based study in Chinese patients

Background

Glaucoma is the irreversible vision loss and contributes second leading cause of blindness worldwide. Matrix metalloproteinase‐9 (MMP‐9) is involved with remodeling and destruction of extracellular matrix. Elevated MMP‐9 levels and various functional variants of MMP‐9 have been associated with glaucoma in different population. In the current investigation, we tested association of MMP‐9 common variants with different clinical categories of glaucoma in Chinese population.

Materials and Methods

We enrolled total of 396 glaucoma patients those reported to hospital comprising of 212 primary angle closure glaucoma (PACG) cases and 184 primary open‐angle glaucoma POAG patients. In addition, 329 normal individuals from similar geographical areas were enrolled as healthy controls. Five common single nucleotide polymorphisms (rs3918242, rs3918254, rs2250889, rs3918249, and rs17576) were genotyped by PCR‐RFLP. Plasma levels of MMP‐9 were quantified by ELISA.

Results

Heterozygotes (GC) and allele “G” for rs2250889 polymorphism were more frequent in PACG cases compared with healthy controls (GC: P < .0001, OR = 2.26; G: P < .0001, OR = 1.19). Similarly, heterozygous mutant and minor allele for rs3918242 polymorphism were more prevalent in POAG in comparison with healthy controls. Interestingly, distribution of rs17576 variant was statistically higher in both PACG and POAG cases than healthy controls. Furthermore, analysis of plasma MMP‐9 with MMP‐9 polymorphisms revealed significant association of rs2250889, rs3918242, and rs17576 with plasma levels of the protein.

Conclusions

MMP‐9 mutants are associated with elevated plasma MMP‐9 and predisposed to development of glaucoma.