Biomedical subjects

P Soloway

Publications and source records attributed to P Soloway.

6 recordsLinked to original sources

PubMed2000

Elevated matrix metalloprotease and angiostatin levels in integrin alpha 1 knockout mice cause reduced tumor vascularization.

Integrin alpha1beta1 is a collagen receptor abundantly expressed on microvascular endothelial cells. As well as being the only collagen receptor able to activate the Ras/Shc/mitogen-activated protein kinase pathway promoting fibroblast cell proliferation, it also acts to inhibit collagen and metalloproteinase (MMP) synthesis. We have observed that in integrin alpha1-null mice synthesis of MMP7 and MMP9 was markedly increased compared with that of their wild-type counterparts. As MMP7 and MMP9 have been shown to generate angiostatin from circulating plasminogen, and angiostatin acts as a potent inhibitor of endothelial cell proliferation, we determined whether tumor vascularization was altered in the alpha1-null mice. Tumors implanted into alpha1-null mice showed markedly decreased vascularization, with a reduction in capillary number and size, which was accompanied by an increase in plasma levels of angiostatin due to the action of MMP7 and MMP9 on circulating plasminogen. In vitro analysis of alpha1-null endothelial cells revealed a marked reduction of their proliferation on both integrin alpha1-dependent (collagenous) and independent (noncollagenous) substrata. This reduction was prevented by culturing alpha1-null cells with plasma derived from plasminogen-null animals, thus omitting the source from which to generate angiostatin. Plasma from tumor-bearing alpha1-null animals uniquely inhibited endothelial cell growth, and this inhibition was relieved by the coaddition of either MMP inhibitors, or antibody to angiostatin. Integrin alpha1-deficient mice thus provide a genetically characterized model for enhanced angiostatin production and serve to reveal an unwanted potential side effect of MMP inhibition, increased tumor angiogenesis.

Angiostatins↗

PubMed1999

The pathogenesis of choroidal neovascularization in patients with age-related macular degeneration.

Laser photocoagulation and several experimental treatments for choroidal neovascularization (CNV) in patients with age-related macular degeneration attempt to ablate the neovascularization, but do not address underlying angiogenic stimuli. As a result, recurrences are a major problem. Drug treatment to counter the growth of CNV would be a major advance, but its development is impeded by lack of knowledge concerning the stimuli and other molecular signals involved in the pathogenesis of CNV. Herein we explore clues that can be gleaned from clinical, epidemiological, pathological, and experimental data. These suggest that abnormalities of the extracellular matrix of retinal pigmented epithelial (RPE) cells may promote a pro-angiogenic RPE phenotype that contributes to the development of CNV. This provides a general hypothesis that can be tested, but it is also necessary to test hypotheses regarding the specific alterations in gene expression that contribute to CNV. Identification of alterations in gene expression will provide targets for rational design of drug treatment.

Choroid Diseases↗

PubMed1998

Endothelial dysfunction following thrombolysis in vitro.

OBJECTIVES: Thrombolytic therapy is frequently used to manage vascular graft thrombosis. However, long-term patency after thrombolysis remains poor. The purpose of this study was to characterise the morphological and functional response of endothelial cells (EC) exposed to a thrombus and subsequently lytic therapy. METHODS: Human EC were exposed to human whole blood thrombus for 2, 6, 12, and 24 h. The thrombus was lysed with urokinase. Cell morphology was studied with electron microscopy. Northern blot analyses were performed with human c-DNA probes for endothelin-1, thrombomodulin, tissue factor, tissue plasminogen activator, plasminogen activator inhibitor, and triose phosphate isomerase. RESULTS: EC retraction occurred for each period of incubation. Thrombomodulin expression was increased 2.2-fold at 6 h and 2.4-fold at 24 h. t-PA expression was depressed proportionally to the duration of thrombus exposure. PAI and TF expression transiently increased 1.5-fold at 2 h of exposure and returned to baseline at 6 h. Endothelin expression remained unchanged. CONCLUSIONS: Except for a transient increase in TF expression and reversal of the tPA/PAI ratio, EC exposed to thrombus do not appear to become actively procoagulant. The increase in TM expression may reflect enhanced thromboresistance. However, EC retraction may be responsible for an increase thrombogenicity of saphenous vein graft after thrombosis and Urokinase therapy.

Cells, Cultured↗

PubMed1997

Assessment of the role of tissue inhibitor of metalloproteinase-1 (TIMP-1) during the periovulatory period in female mice lacking a functional TIMP-1 gene.

Tissue inhibitor of metalloproteinase (TIMP)-1 is a multifunctional peptide that has been implicated in the ovulatory process. To assess the function of TIMP-1 during the periovulatory period in vivo, mice incapable of expressing the TIMP-1 gene product were utilized. Twenty-three-day-old TIMP-1-deficient (n = 59) and wild-type (n = 61) female mice were injected with 5 IU eCG, followed 48 h later by an ovulation-inducing dose of hCG (5 IU). Animals were killed at the time of hCG injection (0-h hCG), at 12 h (12-h hCG), or at 24 h post-hCG (24-h hCG) administration. Serum was collected for the assessment of estradiol-17beta (0-h hCG groups) or progesterone content (12- and 24-h hCG groups), while ovaries were removed for either histological preparation or Northern analysis of TIMP-1, TIMP-2, and TIMP-3. The number of healthy and atretic follicles was determined in the 0-h hCG groups, as was the number of oocytes released in the 24-h hCG group. TIMP-1-deficient females in the 0-h hCG group showed reduced levels of ovarian TIMP-2 (0.29-fold decrease, p < 0.05) and TIMP-3 (3.0-fold decrease, p < 0.05) expression compared to wild-type counterparts. No significant difference was detected between genotypes in the 0-h hCG group for number of healthy or atretic follicles or for serum estradiol-17beta concentrations. Additionally, no significant differences were detected between genotypes in the 12- and 24-h hCG groups for serum progesterone concentrations, ovarian TIMP-2 and TIMP-3 expression, or number of oocytes released (24-h hCG group). To assess the effect of TIMP-1 on steroidogenesis in vitro, granulosa cells were obtained from 23-day-old, eCG-primed TIMP-1-deficient and wild-type females. Addition of recombinant human TIMP-1 significantly increased conditioned media estradiol-17beta concentrations in cell cultures from both mutant (1.32-fold over controls; p = 0.02; n = 4) and wild-type females (1.16-fold over controls; p = 0.04; n = 3). It is concluded from this study that TIMP-1 may modulate ovarian TIMP-2 and TIMP-3 mRNA expression during folliculogenesis. In addition, TIMP-1 exhibits steroidogenic activity in vitro, but no evidence was found for regulation of steroidogenesis in vivo.

Animals↗

PubMed1991

Regulation of the immune response to peptide antigens: differential induction of immediate-type hypersensitivity and T cell proliferation due to changes in either peptide structure or major histocompatibility complex haplotype.

The immunodominant CD4 T cell epitope of the bacteriophage lambda cI repressor protein in several inbred mouse strains can be represented by a peptide encompassing amino acids 12-26. Here, we show that this peptide, and a variety of its sequence variants, can induce immediate-type hypersensitivity in mice. 12-26 variants that differ by as little as single amino acid residues deviate greatly in their ability to induce hypersensitivity. Further, differences in major histocompatibility complex class II alleles appear to be as influential as changes in peptide structure in determining whether hypersensitivity is developed. The ability of a given peptide-class II combination to induce hypersensitivity correlates with production of peptide-specific antibody, but not with ability or inability to induce a T cell proliferative response. Administration of anti-interleukin 4 (IL-4) mAb prevents the development of hypersensitivity, and analysis of cytokine production by T cell hybridomas derived from peptide-immunized mice suggests that whether a given peptide-class II combination can induce hypersensitivity depends on its ability to induce IL-4 production. The data demonstrate that changes in the nature of the epitope(s) recognized by the CD4 T cell population can result in qualitative differences in the response elicited in this population, ultimately leading to dramatic quantitative and qualitative variations in the effector phase of the immune response.

Amino Acid Sequence↗

PubMedDate not supplied

Tissue inhibitor of matrix metalloproteinases-1 impairs arterial neointima formation after vascular injury in mice.

The hypothesis that tissue inhibitor of metalloproteinases-1 (TIMP-1) plays a role in neointima formation was tested with the use of a vascular injury model in wild-type (TIMP-1(+/+)) and TIMP-1-deficient (TIMP-1(-/-)) mice. The neointimal area at 1 to 3 weeks after electric injury of the femoral artery was significantly higher in TIMP-1(-/-) as compared with TIMP-1(+/+) mice (0.012+/-0. 0015 versus 0.0033+/-0.0008 mm(2) at 1 week, P<0.005). The medial areas were comparable, resulting in intima/media ratios that were significantly larger in TIMP-1(-/-) as compared with TIMP-1(+/+) arteries (1.2+/-0.22 versus 0.39+/-0.08 at 1 week, P<0.005). Nuclear cell counts in cross-sectional areas of the intima of the injured region were higher in TIMP-1(-/-) as compared with TIMP-1(+/+) arteries (138+/-15 versus 69+/-8 at 1 week, P<0.005). Immunocytochemical analysis revealed that alpha-actin-positive smooth muscle cells (SMCs) at 2 weeks after injury were more abundant in the intima of TIMP-1(-/-) arteries than in that of TIMP-1(+/+) arteries, whereas after 3 weeks the intimal cell population consisted mainly of SMCs in both genotypes. In in vitro scrape-wounding assays, SMCs of TIMP-1(-/-) mice migrated faster than those of TIMP-1(+/+) mice. Zymography of arterial extracts revealed a higher active matrix metalloproteinase (MMP)-2 level at 1 to 3 weeks after injury in TIMP-1(-/-) arteries, whereas active MMP-9 was only detected in TIMP-1(-/-) arteries at 1 week after injury. These data are compatible with a role of TIMP-1 in the impairment of SMC migration and neointima formation after vascular injury, as a result of inhibition of MMP activity.

Animals↗