Predictive role of coagulation-balance gene polymorphisms in the efficacy of photodynamic therapy with verteporfin for classic choroidal neovascularization secondary to age-related macular degeneration.

OBJECTIVES: Age-related macular degeneration (AMD) represents the leading cause of blindness in Western populations. The majority of severe vision loss occurs in the exudative form of AMD, characterized by the development of choroidal neovascularization (CNV) beneath the fovea. Photodynamic therapy with verteporfin (PDT-V) represents one of the most largely employed modality that maybe achieves the subfoveal CNV inactivation in AMD patients. Although several ocular factors have been hitherto investigated as predictors, these researches have weakly contributed to PDT-V optimization. As PDT-V benefit is determined by CNV photothrombosis, we have retrospectively studied several coagulation-balance gene polymorphisms as predictors of PDT-V efficacy. METHODS: Ninety Caucasian patients with neovascular AMD were subdivided in responder and nonresponder, on the basis of CNV responsiveness to PDT-V application. Six gene polymorphisms, that is factor V G1691A, prothrombin G20210A, factor XIII-A G185T, methylenetetrahydrofolate reductase C677T, methionine synthase A2756G, and methionine synthase reductase A66G, were genotyped in the entire cohort. RESULTS: Logistic regression models showed that PDT-V responders were more prevalent within patients with prothrombin G20210A mutation [odds ratio (OR)=5.6, 95% confidence interval (CI) (1.2, 27.2), P=0.03], and within methylenetetrahydrofolate reductase 677T carriers [OR=6.9, 95% CI (2.7, 18.1), P<0.001]. Conversely, PDT-V nonresponders were overrepresented in carriers for factor XIII-A 185T [OR=0.13, 95% CI (0.05, 0.36), P<0.001]. CONCLUSION: These results provide evidences for the presence of pharmacogenetic relationship between peculiar coagulation-balance gene polymorphisms and different levels of PDT-V effectiveness in patients with AMD-related CNV.

Factor XIII contrasts the effects of metalloproteinases in human dermal fibroblast cultured cells.

Matrix metalloproteinases (MMPs) are overexpressed in venous leg ulcers, determining a breakdown of the main extracellular matrix (ECM) components owing mainly to collagenase activities, and so playing a crucial role in ulcer pathogenesis. The authors studied the effects of coagulation factor XIII (FXIII), which cross-links collagen and other ECM components, in human fibroblast cultured cells in the presence and in the absence of matrix metalloproteinases from Clostridium histolyticum collagenase. Clostridium collagenase at concentrations of 2.0, 1.0, and 0.5 mg/mL was added to normal human dermal fibroblasts cultured in the presence of 0.0, 1.0, and 5.0 U/mL of FXIII concentrate (Fibrogammin P, Aventis Behring). Cell counting and metabolically active fibroblast evaluation in the cultures were monitored for 72 hours, by means of trypan-blue dye and MTT test, respectively. The MTT test showed that at the highest collagenase concentration (2.0 mg/mL), the cell number decreased more than 95% in 72 hours of treatment and no significant differences were observed regardless of the FXIII concentrations utilized. At lower collagenase concentration (1.0 mg/mL), in absence or in presence of FXIII (1.0 U/mL), the cell number decreased by about 80% in 72 hours. In contrast, in the presence of higher FXIII levels (5.0 U/mL), cells suffered globally significantly less collagenase effects (p = 0.011) and the gain was appreciable at each time tested. Finally, at 0.5 mg/mL of collagenase concentration, in the absence of FXIII, the cell number decreased by about 60% in 72 hours, whereas in presence of FXIII 1.0 U/mL and 5.0 U/mL, cells decreased significantly less, by about 35% and 20%, respectively (p < 0.025 and p < 0.01, respectively). These data were also confirmed by direct cell counting utilizing the trypan-blue test. Factor XIII contrasts effectively the detrimental action of Clostridium collagenases in human fibroblast cultured cells. These results support several in vivo reports about the effectiveness of its topical application in order to enhance the venous ulcer healing processes.

Prevalence of factor XIII Val34Leu polymorphism in patients affected by spontaneous subconjunctival hemorrhage.

PURPOSE: To verify the prevalence of Val34Leu polymorphism in factor XIII A-chain gene (FXIII Val34Leu) in patients with spontaneous subconjunctival hemorrhage (SCH). DESIGN: Nonrandomized case-control study. METHODS: One hundred seven white patients suffering from one or more episodes of idiopathic SCH and 107 healthy subjects were matched for age and gender, and genotyped for FXIII Val34Leu. Anamnestic, ophthalmologic, cardiovascular, and serologic examinations were performed. RESULTS: Frequency of FXIII mutated allele (Leu34) was significantly higher in SCH patients than in controls. Computing together heterozygotes (Val/Leu) and homozygotes (Leu/Leu), genotype distribution was statistically different. In a conditional logistic regression model, the comparison of the three separated genotypes, performed among 25 patients with recurrent idiopathic SCHs and controls, gave significant differences for both Val/Leu and Leu/Leu variables. CONCLUSION: Both homozygosity and heterozygosity for FXIII Val34Leu predispose to idiopathic SCH, emphasizing the role of Leu34 allele as inherited risk factor for spontaneous, especially recurrent, SCHs.

Recurrent episodes of spontaneous subconjunctival hemorrhage in patients with factor XIII Val34Leu mutation.

PURPOSE: To report on the occurrence of frequent episodes of spontaneous subconjunctival hemorrhage (SCH) in patients with the Leu 34 allele of the coagulation factor XIII (FXIII), known to be associated with high hemorrhagic risk. DESIGN: Observational case series. METHODS: Five young adults who had suffered from recurrent idiopathic SCH not associated with any recognized ocular and systemic hemorrhagic risk factor were investigated. Accurate anamnestic, ophthalmologic, hematologic, and serologic examinations were performed, together with blood pressure measurements, electrocardiogram (ECG), and 24-hour Holter ECG recordings. FXIII Val34Leu polymorphism was studied by DNA chain polymerase reaction. RESULTS: DNA analyses showed that the hemorrhagic mutated Leu34 allele was present in four of our selected patients: two mutated homozygotes (Leu/Leu) and two heterozygotes (Val/Leu). In the last subject this polymorphism was not detected. All the other clinical evaluations did not disclose any significant abnormality. CONCLUSIONS: The FXIII Val34Leu mutation may be associated with an increased risk for spontaneous episodes of SCH.