Aortic valve disease and gamma-glutamyltransferase: accumulation in tissue and relationships with calcific degeneration.

Abstract OBJECTIVE: Degenerative aortic valve disease is characterized by some of the histological features of atherosclerotic lesions. Gamma-glutamyltransferase (GGT) has been recently implicated in pathogenesis of atherosclerosis, as well as in modulation of cells involved in calcium metabolism. We aimed to evaluate the possible implication of this enzyme activity in aortic valve disease. METHODS: GGT immunohistochemistry was performed on valve leaflets of 64 patients with aortic valve stenosis undergoing valve replacement. Fractional GGT activity in plasma and tissue was analysed in a subgroup of cases by molecular exclusion chromatography. RESULTS: A close association was found between tissue extracellular GGT staining and lipid deposits (p<0.0001). GGT was expressed by CD68-positive cells around neovessels, as well as by MMP-9- and TRAP-positive multinucleated cells in the vicinity of bone metaplasia areas. Total plasma GGT levels were associated with low HDL-c (p=0.028) and high triglycerides (p=0.017). Total GGT activity in tissue was negatively correlated with the extent of valves calcification (p=0.03). Both serum and tissue GGT levels were negatively associated with severity of valve stenosis, as judged by peak transvalvular pressure gradients (p<0.0003 and p<0.002, respectively). CONCLUSIONS: Accumulation of GGT activity inside the lipid component of valves leaflets suggests a common mechanism of lesion shaping underlying both atherosclerosis and degenerative aortic valve disease. Moreover, the finding of GGT expression in cells with an osteoclast-like phenotype, and its negative correlation with both valves calcification and degree of valvular stenosis lend additional support to the recently envisaged involvement of GGT in the homeostasis of calcified tissues

Biological features (inflammation and neoangiogenesis) and atherosclerotic risk factors in carotid plaques and calcified aortic valve stenosis: two different sites of the same disease?

Neoangiogenesis and inflammation have a pivotal role in atherosclerosis. Observations support the hypothesis that calcified aortic valve stenosis is an inflammatory process, similar to atherosclerosis in tissue features and risk factors. We studied 2 groups of cases: 47 were affected by hemodynamic atherosclerotic carotid plaque (group 1) and 35 by severe calcified aortic valve stenosis (group 2). We compared the groups for atherosclerosis risk factors, morphologic features, and immunohistochemical phenotypes. In both groups, men, smokers, and hypertensive subjects prevailed, and histologic analysis showed an elevated score for T-lymphocyte infiltrates, neoangiogenesis, calcium, and sclerosis. Adhesion molecule expression was present in both lesions. Expression of intercellular adhesion molecule 1 correlated with inflammatory infiltrates (group 1, P = .0007; group 2, P = .06). Neoangiogenesis also correlated with inflammatory infiltrates (group 1, P = .035; group 2, P = .045). In valves, neoangiogenesis correlated with calcium (P = .048). Carotid plaque and calcified valve stenosis showed common risk factors and biologic hallmarks of a chronic inflammatory process. Inflammation and neoangiogenesis have a crucial role in plaque evolution and in the progression of aortic valve stenosis

Aortic valve disease and gamma-glutamyltransferase: accumulation in tissue and relationships with calcific degeneration.

OBJECTIVE: Degenerative aortic valve disease is characterized by some of the histological features of atherosclerotic lesions. Gamma-glutamyltransferase (GGT) has been recently implicated in pathogenesis of atherosclerosis, as well as in modulation of cells involved in calcium metabolism. We aimed to evaluate the possible implication of this enzyme activity in aortic valve disease. METHODS: GGT immunohistochemistry was performed on valve leaflets of 64 patients with aortic valve stenosis undergoing valve replacement. Fractional GGT activity in plasma and tissue was analysed in a subgroup of cases by molecular exclusion chromatography. RESULTS: A close association was found between tissue extracellular GGT staining and lipid deposits (p<0.0001). GGT was expressed by CD68-positive cells around neovessels, as well as by MMP-9- and TRAP-positive multinucleated cells in the vicinity of bone metaplasia areas. Total plasma GGT levels were associated with low HDL-c (p=0.028) and high triglycerides (p=0.017). Total GGT activity in tissue was negatively correlated with the extent of valves calcification (p=0.03). Both serum and tissue GGT levels were negatively associated with severity of valve stenosis, as judged by peak transvalvular pressure gradients (p<0.0003 and p<0.002, respectively). CONCLUSIONS: Accumulation of GGT activity inside the lipid component of valves leaflets suggests a common mechanism of lesion shaping underlying both atherosclerosis and degenerative aortic valve disease. Moreover, the finding of GGT expression in cells with an osteoclast-like phenotype, and its negative correlation with both valves calcification and degree of valvular stenosis lend additional support to the recently envisaged involvement of GGT in the homeostasis of calcified tissues

Epigenetic and copy number variation analysis in retinoblastoma by MS-MLPA.

Retinoblastoma is the most common primary intraocular malignancy in children. Two step inactivation of RB1 (M1-M2) represents the key event in the pathogenesis of retinoblastoma but additional genetic and epigenetic events (M3-Mn) are required for tumor development. In the present study, we employed Methylation Specific Multiplex Ligation Probe Assay to investigate methylation status and copy number changes of 25 and 39 oncosuppressor genes, respectively. This technique was applied to analyse 12 retinoblastomas (5 bilateral and 7 unilateral) and results were compared to corresponding normal retina. We identified hypermethylation in seven new genes: MSH6 (50%), CD44 (42%), PAX5 (42%), GATA5 (25%), TP53 (8%), VHL (8%) and GSTP1 (8%) and we confirmed the previously reported hypermethylation of MGMT (58%), RB1 (17%) and CDKN2 (8%). These genes belong to key pathways including DNA repair, pRB and p53 signalling, transcriptional regulation, protein degradation, cell-cell interaction, cellular adhesion and migration. In the same group of retinoblastomas, a total of 29 copy number changes (19 duplications and 10 deletions) have been identified. Interestingly, we found deletions of the following oncosuppressor genes that might contribute to drive retinoblastoma tumorigenesis: TP53, CDH13, GATA5, CHFR, TP73 and IGSF4. The present data highlight the importance of epigenetic changes in retinoblastoma and indicate seven hypermethylated oncosuppressors never associated before to retinoblastoma pathogenesis. This study also confirms the presence of copy number variations in retinoblastoma, expecially in unilateral cases (mean 3 ± 1.3) where these changes were found more frequently respect to bilateral cases (mean 1.4 ± 1.1)

Advances in Alport syndrome diagnosis using next-generation sequencing.

Alport syndrome (ATS) is a hereditary nephropathy often associated with sensorineural hypoacusis and ocular abnormalities. Mutations in the COL4A5 gene cause X-linked ATS. Mutations in COL4A4 and COL4A3 genes have been reported in both autosomal recessive and autosomal dominant ATS. The conventional mutation screening, performed by DHPLC and/or Sanger sequencing, is time-consuming and has relatively high costs because of the absence of hot spots and to the high number of exons per gene: 51 (COL4A5), 48 (COL4A4) and 52 (COL4A3). Several months are usually necessary to complete the diagnosis, especially in cases with less informative pedigrees. To overcome these limitations, we designed a next-generation sequencing (NGS) protocol enabling simultaneous detection of all possible variants in the three genes. We used a method coupling selective amplification to the 454 Roche DNA sequencing platform (Genome Sequencer junior). The application of this technology allowed us to identify the second mutation in two ATS patients (p.Ser1147Phe in COL4A3 and p.Arg1682Trp in COL4A4) and to reconsider the diagnosis of ATS in a third patient. This study, therefore, illustrates the successful application of NGS to mutation screening of Mendelian disorders with locus heterogeneity

Advances in Alport syndrome diagnosis using next-generation sequencing.

Alport syndrome (ATS) is a hereditary nephropathy often associated with sensorineural hypoacusis and ocular abnormalities. Mutations in the COL4A5 gene cause X-linked ATS. Mutations in COL4A4 and COL4A3 genes have been reported in both autosomal recessive and autosomal dominant ATS. The conventional mutation screening, performed by DHPLC and/or Sanger sequencing, is time-consuming and has relatively high costs because of the absence of hot spots and to the high number of exons per gene: 51 (COL4A5), 48 (COL4A4) and 52 (COL4A3). Several months are usually necessary to complete the diagnosis, especially in cases with less informative pedigrees. To overcome these limitations, we designed a next-generation sequencing (NGS) protocol enabling simultaneous detection of all possible variants in the three genes. We used a method coupling selective amplification to the 454 Roche DNA sequencing platform (Genome Sequencer junior). The application of this technology allowed us to identify the second mutation in two ATS patients (p.Ser1147Phe in COL4A3 and p.Arg1682Trp in COL4A4) and to reconsider the diagnosis of ATS in a third patient. This study, therefore, illustrates the successful application of NGS to mutation screening of Mendelian disorders with locus heterogeneity

p53 Arg72Pro and MDM2 309 SNPs in hereditary retinoblastoma.

The tumor suppressor p53 and its negative regulator MDM2 have crucial roles in a variety of cellular functions such as the control of the cell cycle, senescence, genome stability and apoptosis, and are frequently deregulated in carcinogenesis. Previous studies have highlighted the contribution of the common functional polymorphisms p53 p.Arg72Pro and MDM2 309SNP to the risk of both common cancers and Li-Fraumeni syndrome. Their possible role in retinoblastoma has recently been addressed by Castéra et al, who however only studied the MDM2 309SNP. Here, for the first time, we analyzed both single nucleotide polymorphisms (SNPs) in a case-control study of 111 Italian hereditary retinoblastoma patients. We found a significant association of the p53 Pro/Pro genotype with the disease (odds ratio=3.58, P=0.002). The MDM2 309SNP showed a weak negative association of allele G that deserves further investigation. These findings further support the hypothesis that genetic variability of the p53 pathway contributes to the individual susceptibility to retinoblastoma, as shown for Li-Fraumeni syndrome and a variety of non-hereditary cancers