Pleiotropic effects of YC-1 selectively inhibit pathological retinal neovascularization and promote physiological revascularization in a mouse model of oxygen-induced retinopathy.

Vascular endothelial growth factor (VEGF) and inducible nitric-oxide synthase (iNOS) have been implicated in ischemia-induced retinal neovascularization. Retinal ischemia has been shown to induce VEGF and iNOS expression. It has been postulated that one of the crucial consequences of iNOS expression in the ischemic retina is the inhibition of angiogenesis. Furthermore, iNOS was shown to be overexpressed in Müller cells from patients with diabetic retinopathy. YC-1, a small molecule inhibitor of hypoxia-inducible factor (HIF)-1 alpha, has been shown to inhibit iNOS expression in various tissue models. Our aim was to assess the pleiotropic effects of YC-1 in an oxygen-induced retinopathy (OIR) mouse model and evaluate its therapeutic potential in HIF-1- and iNOS-mediated retinal pathologies. Dual-injections of YC-1 into the neovascular retinas decreased the total retinopathy score, inhibited vaso-obliteration and pathologic tuft formation, and concomitantly promoted physiological retinal revascularization, compared with dimethyl sulfoxide (DMSO)-treated group. Furthermore, YC-1-treated retinas exhibited a marked increase in immunoreactivities for CD31 and von Willebrand factor and displayed significant inhibition in HIF-1alpha protein expression. Furthermore, YC-1 down-regulated VEGF, erythropoietin, endothelin-1, matrix metalloproteinase-9, and iNOS message and protein levels. When hypoxic Müller and neuoroglial cells were treated with YC-1, iNOS mRNA and protein levels were reduced in a dose-dependent fashion. We demonstrate that YC-1 inhibits pathological retinal neovascularization by exhibiting antineovascular activities, which impaired ischemia-induced expression of HIF-1 and its downstream angiogenic molecules. Furthermore, YC-1 enhanced physiological revascularization of the retinal vascular plexuses via the inhibition of iNOS mRNA and protein expressions. The pleiotropic effects of YC-1 allude to its possible use as a promising therapeutic iNOS inhibitor candidate for the treatment of retinal neovascularization.

Modulating the hypoxia-inducible factor signaling pathway as a therapeutic modality to regulate retinal angiogenesis.

Hypoxia-inducible factor (HIF) signaling cascade plays a critical role in angiogenesis by activating the transcription of genes encoding angiogenic growth factors. This study evaluated the effects of YC-1, a HIF-1 inhibitor, on the morphological, biochemical and molecular changes in human retinal microvascular endothelial cells. We found that YC-1 suppressed vascular endothelial cell proliferation, migration and tube formation, while it significantly increased the proteasome activity. Moreover, YC-1 induced a G(0)/G(1) cell-cycle arrest, whereas it exerted only an insignificant proapoptotic effects. Under normoxia or hypoxia, YC-1 did not alter the morphology or the cell viability. Additionally, under hypoxic conditions, YC-1 downregulated HIF-2alpha, VEGF, EPO, ET-1, and MMP-9 mRNA and protein levels, this was accompanied by a significant decrease in the MMP-9 activity. YC-1 decreased the basal expression of HIF-1alpha protein under normoxia, whereas it inhibited HIF-1alpha protein synthesis, stability, and nuclear translocation mechanisms under hypoxia. Furthermore, in a 3D collagen matrix model using mouse retinal explants cultured under normoxic and hypoxic conditions, YC-1; (1) inhibited outgrowth of new vessel sprouts; (2) reduced VEGF expression; (3) dramatically decreased the vessels immunoreactivities for CD31 and von Willebrand Factor (vWF); and (4) was highly effective in reducing the vascular density within the retina, compared to controls. These findings indicate that YC-1 possesses several antiangiogenic properties, both in vitro and ex vivo, which could be exploited as valuable therapeutic potentials to inhibit formation and the growth of new retinal vessels in the hypoxic retina.

High-throughput genotyping of single nucleotide polymorphisms with rolling circle amplification.

BACKGROUND: Single nucleotide polymorphisms (SNPs) are the foundation of powerful complex trait and pharmacogenomic analyses. The availability of large SNP databases, however, has emphasized a need for inexpensive SNP genotyping methods of commensurate simplicity, robustness, and scalability. We describe a solution-based, microtiter plate method for SNP genotyping of human genomic DNA. The method is based upon allele discrimination by ligation of open circle probes followed by rolling circle amplification of the signal using fluorescent primers. Only the probe with a 3' base complementary to the SNP is circularized by ligation. RESULTS: SNP scoring by ligation was optimized to a 100,000 fold discrimination against probe mismatched to the SNP. The assay was used to genotype 10 SNPs from a set of 192 genomic DNA samples in a high-throughput format. Assay directly from genomic DNA eliminates the need to preamplify the target as done for many other genotyping methods. The sensitivity of the assay was demonstrated by genotyping from 1 ng of genomic DNA. We demonstrate that the assay can detect a single molecule of the circularized probe. CONCLUSIONS: Compatibility with homogeneous formats and the ability to assay small amounts of genomic DNA meets the exacting requirements of automated, high-throughput SNP scoring.

A novel mutation in purine nucleoside phosphorylase in a child with normal uric acid levels.

BACKGROUND: Purine nucleoside phosphorylase (PNP) deficiency is an autosomal recessive disease in which affected children present with recurrent infection and may present with failure to thrive, neurological impairment, autoimmunity, or malignancy. The diagnosis of PNP is usually suggested by a reduced level of serum uric acid. We report here a novel mutation in the nucleoside phosphorylase gene (NP gene) in a patient with primary immunodeficiency and neurological impairment but with normal uric acid levels. The diagnosis was confirmed biochemically and showed a reduced PNP activity, and also by molecular gene analysis. METHODS: A case report and a complete NP gene DNA analysis. RESULT: The sequencing analysis showed a novel homozygous missense mutation, c.487T>C in the NP gene, resulting in a substitution of serine by proline at residue 163 (S163P) in the mature NP protein. CONCLUSION: This NP missense mutation reported here is associated with recurrent infection, developmental delay, and primary immunodeficiency combined with normal uric acid levels in the affected child most likely due to a residual PNP enzyme activity. PNP deficiency causing primary immunodeficiency is still possible, even with normal uric acid levels.

Identification of a common novel mutation in Saudi patients with argininosuccinic aciduria.

We have identified a common novel mutation (Q354X) in the argininosuccinate lyase (ASL) gene in Saudi patients with argininosuccinic aciduria (ASAuria; McKusick 207900). The two index patients were siblings, had a neonatal onset of the disease and were diagnosed based on the clinical presentation and confirmed by analysis of their dried blood spots (DBS) by tandem mass spectrometry (MS/MS). The ASL gene was then analysed by direct sequencing. A further 28 patients with a confirmed diagnosis of ASAuria based on MS/MS of their DBS were tested by sequencing for the presence of the Q354X mutation. This mutation was found in 14 out of the 28 patients (50%) tested. Our work indicates that the Q354X allele is common, may account for 50% of the abnormal ASL genes in the Saudi population, and is likely to be associated with the neonatal form of the disease. We recommend that all patients diagnosed with ASAuria in Saudi Arabia or of Arab origin be tested for this mutation and for Q116X, which has been described previously. In addition, further analysis is needed to identify other underlying disease mutations for ASAuria in the Saudi population.

Antibody-dependent cellular cytotoxicity directed against cells expressing human immunodeficiency virus type 1 envelope of primary or laboratory-adapted strains by human and chimpanzee monoclonal antibodies of different epitope specificities.

The characteristics of antibody-dependent cellular cytotoxicity (ADCC) directed by a panel of human and chimpanzee antienvelope (anti-Env) monoclonal antibodies (MAbs) of different epitope specificities were studied; this was accomplished by using target cells expressing human immunodeficiency virus type 1 (HIV-1) Envs of either primary or laboratory-adapted strains. Human MAbs of similar apparent affinities (1 x 10(9) to 2 x 10(9) liters/mol) against either a "cluster II"-overlapping epitope of gp41 or against the CD4 binding site, V3 loop, or C5 domain of gp120 directed substantial and comparable levels of specific lysis against targets infected with laboratory-adapted strains of HIV-1. As expected, those MAbs specific for relatively conserved regions of Env generally exhibited ADCC activity against a broader range of HIV-1 strains than those directed against variable epitopes. Significant ADCC activities of selected MAbs against primary isolate Env-expressing cells were demonstrated. In addition, a new ADCC epitope in the V2 domain of gp120 was defined. CD56+ cells were demonstrated to be the effector cells in these studies by fluorescence-activated cell sorting followed by ADCC assays. Notably, all anti-Env MAbs tested in this study, including MAbs directed against each of the known neutralization epitope clusters in gp120, directed significant levels of ADCC against targets expressing Env of one or more HIV-1 strains. These results imply that many, if not most, HIV-1-neutralizing human Abs of high affinity (> or = 3 x 10(8) liters/mol in these studies) and of the immunoglobulin G1 (IgG1) subclass (i.e., the predominate IgG subclass) are capable of directing ADCC. Since neutralizing Abs have been associated with long-term survival following HIV-1 infection, this suggests that ADCC activity may be beneficial in vivo.

A novel antibody-dependent cellular cytotoxicity epitope in gp120 is identified by two monoclonal antibodies isolated from a long-term survivor of human immunodeficiency virus type 1 infection.

Two monoclonal antibodies (MAbs), 42F and 43F, were isolated some 14 months apart from a single long-term survivor of human immunodeficiency virus type 1 (HIV-1) infection. These MAbs were found to be indistinguishable in terms of their isotypes, specificities, affinities, and biological activities. Both 42F and 43F directed substantial antibody-dependent cellular cytotoxicity (ADCC) against cells infected with four divergent lab-adapted strains of HIV-1, but no neutralizing activity against these strains was detectable. The ability of MAbs 42F and 43F, as well as that of MAbs against two other gp120 epitopes, to direct ADCC against uninfected CD4+ cells to which recombinant gp120SF2 had been adsorbed (i.e., "innocent bystanders") was demonstrated to be less efficient by at least an order of magnitude than their ability to direct ADCC against HIV-1-infected cells. Flow cytometry analyses showed that 42F and 43F also bind to native primary isolate Envs from clades B and E expressed on cell surfaces. By direct binding and competition assays, it was demonstrated that the 42F/43F epitope lies in a domain of gp120 outside the previously described CD4-binding site and V3 loop ADCC epitope clusters. Immunoblot analysis revealed that the 42F/43F epitope is not dependent on disulfide bonds or N-linked glycans in gp120. Epitope mapping of 42F and 43F by binding to linear peptides demonstrated specificity of these MAbs for a sequence of 10 amino acids in the C5 domain comprising residues 491 to 500 (Los Alamos National Laboratory numbering for the HXB2 strain). Thus, 42F and 43F define a new ADCC epitope in gp120. Because of the relative conservation of this epitope and the fact that it appears to have been significantly immunogenic in the individual from which these MAbs were derived, it may prove to be a useful component of HIV vaccines. Furthermore, these MAbs may be used as tools to probe the potential importance of ADCC as an antiviral activity in HIV-1 infection.