Muhammad Khizar Niazi

Role of ACE and PAI-1 Polymorphisms in the Development and Progression of Diabetic Retinopathy.

In the present study we determined the association of angiotensin converting enzyme (ACE) and plasminogen activator inhibitor-1 (PAI-1) gene polymorphisms with diabetic retinopathy (DR) and its sub-clinical classes in Pakistani type 2 diabetic patients. A total of 353 diabetic subjects including 160 DR and 193 diabetic non retinopathy (DNR) as well as 198 healthy controls were genotyped by allele specific polymerase chain reaction (PCR) for ACE Insertion/Deletion (ID) polymorphism, rs4646994 in intron 16 and PAI-1 4G/5G (deletion/insertion) polymorphism, rs1799768 in promoter region of the gene. To statistically assess the genotype-phenotype association, multivariate logistic regression analysis was applied to the genotype data of DR, DNR and control individuals as well as the subtypes of DR. The ACE genotype ID was found to be significantly associated with DR (p = 0.009, odds ratio (OR) 1.870 [95% confidence interval (CI) = 1.04–3.36]) and its sub-clinical class non-proliferative DR (NPDR) (p = 0.006, OR 2.250 [95% CI = 1.098–4.620]), while PAI polymorphism did not show any association with DR in the current cohort. In conclusion in Pakistani population the ACE ID polymorphism was observed to be significantly associated with DR and NPDR, but not with the severe form of the disease i.e. proliferative DR (PDR).

TNF-α Genetic Predisposition and Higher Expression of Inflammatory Pathway Components in Keratoconus

Purpose To date keratoconus (KC) pathogenesis is undefined; however, the involvement of inflammatory pathways in disease development is becoming apparent. In the present study, we investigated the role of a promoter region polymorphism rs1800629 (-308G>A) in the inflammatory pathway component TNF-α and its effects on the expression of TNF-α and downstream molecules tumor necrosis factor receptor 1 and 2 (TNFR1 and TNFR2), v-rel avian reticuloendotheliosis viral oncogene homolog A (RELA), and interleukin 6 (IL-6) in KC development. Methods TNF-α promoter polymorphism rs1800629 (-308G>A), was genotyped in 257 sporadic KC patients and 253 healthy controls. Enzyme-linked immunosorbent assay (ELISA) was performed to assess for the -308G>A genotypes. Quantitative polymerase chain reaction (qPCR) was carried out to compare the mRNA expression of TNF-α, TNFR1, TNFR2, RELA, and IL6 in the corneal tissues of 20 KC patients and 20 donor controls. Results The -308G>A genotype GA was found to be significantly associated with KC development (dominant model [odds ratio (OR) = 6.67 (95% confidence interval [CI] = 4.28-10.42), P < 0.001]) and allele-A (OR = 4.30, 95%CI = 2.93-6.34, P < 0.001). TNF-α serum levels were significantly raised in patients with GA genotype (196.5 ± 69.5 pg/mL) compared to reference genotype GG (21.7 ± 8.2 pg/mL) (P < 0.0001). There was a significant overexpression of TNF-α (P = 0.002), TNFR2 (P = 0.0001), RELA (P = 0.0117), and IL6 (P = 0.0007) in the KC corneal tissues as compared to the control. Conclusions The GA genotype of the TNF-α -308G>A polymorphism is a significant genetic risk factor for the pathogenesis of KC. Moreover, this single nucleotide polymorphism (SNP) was observed to be associated with deregulated expression of downstream molecules, thus further reinforcing the role of the inflammatory pathway components in the development of KC.