CD3-dependent increase in cyclic AMP in human T-cells following stimulation of the CD2 receptor.

We have previously shown that stimulation of the Ti/CD3 receptor complex on human T-cells potentiates adenylate cyclase activation by adenosine or forskolin. Anti-CD2 receptor antibodies shared with anti-CD3 antibodies the ability to potentiate dose dependently the adenosine- and forskolin-stimulated cyclic adenosine monophosphate (cAMP) accumulation, whereas stimulation of the CD45 receptor had no effect on cyclase activity. Modulation of the CD3 complex with anti-CD3 antibodies was found to decrease the CD2 receptor effect on adenylate cyclase activity greatly. The possible involvement of CD3-stimulated phospholipase C (PLC) activation on the cAMP potentiation was examined using HPB-ALL cells that express a CD3 complex with a defect coupling to PLC. Stimulation of the CD3 complex on HPB-ALL cells had only slight effects on adenosine-stimulated cAMP formation, whereas the effect on forskolin-stimulated cAMP was virtually unchanged. The CD3 effect was further analyzed in Jurkat cell membranes. In contrast to the results obtained after stimulation of intact cells, it was found that OKT3 stimulation of membranes did not potentiate the forskolin response. Finally, we tested whether inhibition of endogenous adenylate cyclase agonist production affected the CD3 effect. Inhibition of adenosine production or adenosine breakdown with 8-p-sulphophenyl theophylline (8-PST) or adenosine deaminase (ADA), respectively, did not alter the CD3 effects. Indometacin, which inhibits prostaglandin production, also had no effect. Together, these data show that stimulation of the CD2 receptor potentiates adenylate cyclase responses by a mechanism that is dependent on CD3 expression. Furthermore, the CD3 effect on cAMP appears to be mediated by two different mechanisms, one which is, and one which is not dependent on PLC. Finally, this effect is not due to an endogenous production of adenylate cyclase agonists.

Stimulation of T-cells with OKT3 antibodies increases forskolin binding and cyclic AMP accumulation.

It has recently been shown that elevation of cAMP by adenosine receptor stimulation may be potentiated by stimulation of the T-cell receptor/CD3 complex on human T-cells with the monoclonal antibody OKT3, and that this is mimicked by activation of protein kinase C [Kvanta, A. et al. (1989) Naunyn-Schmeideberg's Arch. Pharmac. 340, 715-717]. In this study the diterpene forskolin, which binds to and activates the adenylate cyclase, has been used to examine further how the CD3 complex may influence the adenylate cyclase pathway. Stimulation with OKT3 alone was found to cause a small dose-dependent increase in basal cAMP accumulation. When combining OKT3 with a concentration of forskolin (10 microM), which by itself had little effect on the cyclase activity, the cAMP accumulation was markedly potentiated. This potentiation was paralleled by an increase in [3H]forskolin binding to saponine permeabilized Jurkat cells from 24 to 41 fmol/10(6) cells. The OKT3 effect on cAMP was blocked by chelating extracellular Ca2+ with EGTA or intracellular Ca2+ with BAPTA and also by W-7, an inhibitor of calmodulin, but was unaffected by H-7, an inhibitor of protein kinase C. Even though OKT3 caused an increase in inositolphosphate turnover, and activated protein kinase C, neither phorbol 12,13 dibutyrate (PDBu) nor the Ca2(+)-ionophore A23187 could mimic the OKT3 effect, whereas a combination of PDBu and A23187 at high concentrations could potentiate forskolin stimulated cyclase activity. Together, these results indicated that stimulation of the CD3 complex could influence the adenylate cyclase by two different mechanisms, one involving activation of protein kinase C and another which does not.

Mitogen stimulation of T-cells increases c-Fos and c-Jun protein levels, AP-1 binding and AP-1 transcriptional activity.

We have analysed the effect of mitogenic lectins on c-Fos and c-Jun protein levels as well as on activator protein-1 (AP-1) binding and enhancer activity in Jurkat T-cells. Both c-Fos and c-Jun protein levels were increased after Con A and PHA stimulation. Since T-cell stimulation increases both intracellular Ca2+ and cAMP levels and activates protein kinase C (PKC), the possible involvement of these intracellular messengers in c-Fos and c-Jun induction was tested. PMA, which directly activates PKC, mimicked the effect of the lectins on c-Fos and c-Jun, but elevation of either intracellular Ca2+ or cAMP levels had little or no effect. The mitogen-induced increase of c-Fos and c-Jun immunoreactivity was inhibited by H-7, a kinase inhibitor with relatively high specificity for PKC, and less efficiently by H-8, a structurally related kinase inhibitor less active on PKC, but more active on cyclic nucleotide-dependent kinases. Con A stimulation was found to increase both binding of AP-1 to the AP-1 consensus sequence, TRE, and AP-1 enhancer activity, in Jurkat cells. PMA was also found to increase the AP-1 enhancer activity, whereas elevation of Ca2+ or cAMP had only minor effects. We conclude that stimulation with mitogenic lectins is sufficient to increase both c-Fos and c-Jun protein levels, AP-1 binding and AP-1 enhancer activity in Jurkat cells and that they act via mechanisms that could involve the activation of PKC.

Translocation of the alpha- and beta-isoforms of protein kinase C following activation of human T-lymphocytes.

We have analyzed how activation of human Jurkat T-cells by the mitogenic lectin, concanavalin A (Con A), may affect the cellular distribution of the alpha- and beta-isoforms of protein kinase C (PKC) in T-cells. In non-stimulated cells almost all of the alpha- and beta-PKC was localized to the cytoplasmic compartment. Stimulation with Con A caused a transient translocation of both alpha- and beta-PKC from the cytoplasm to the cell membrane. The alpha-isoform appeared to be translocated to a somewhat greater extent and for a longer period of time than the beta-form. Translocation was maximal between 1 and 5 min for both of the isoforms. 30 min after stimulation, beta-PKC had returned to basal levels, whereas a substantial amount of alpha-PKC remained associated with the particulate fraction. We conclude that activation of human T-cells causes the translocation of at least two different isoforms of PKC, alpha-PKC and beta-PKC.

CD3/T-cell receptor coupling to a pertussis and cholera toxin-insensitive G-protein.

We have analyzed the effect of CD3/T-cell receptor stimulation on GTP hydrolysis and GTP binding. We show that stimulation of Jurkat, T-cell, membranes with OKT3 results in a 50% increase in GTP hydrolysis which is specifically inhibited by GDP. Pretreatment of the membranes with neither pertussis toxin nor cholera toxin inhibited the GTP hydrolysis. We also show that stimulation with OKT3 increases the binding of GTP gamma S to Jurkat membranes. These data strongly implicate the involvement of a G-protein in CD3/T-cell receptor signalling.

Subfoveal fibrovascular membranes in age-related macular degeneration express vascular endothelial growth factor.

PURPOSE: Vascular endothelial growth factor (VEGF) is a potent and specific angiogenic growth factor, in vitro and in vivo, that may be associated with the development of intraocular neovascularization. In the current study, the authors analyze the expression of VEGF in subfoveal fibrovascular membranes from patients with age-related macular degeneration. METHODS: Surgically removed subfoveal fibrovascular membranes from 18 eyes were analyzed for the expression of VEGF mRNA and protein using in situ hybridization and immunohistochemistry, respectively. RESULTS: Most specimens expressed both VEGF mRNA and protein. The VEGF mRNA expression was particularly high in areas with a marked inflammatory response, in which the expression was concentrated to cells resembling fibroblasts and to surrounding inflammatory cells. VEGF protein expression was seen in fibrovascular parts of the membranes and was predominantly localized to the cytoplasm of fibroblastlike cells. In some of these membranes, strong VEGF protein immunoreactivity also was concentrated to extracellular matrix foci within the fibrovascular stroma. CONCLUSIONS: Results indicate that VEGF may be of pathogenetic importance for the development of the choroidal neovascularization (age-related macular degeneration) and also may implicate a role of fibroblasts of presumable choroidal origin in this process.

Matrix metalloproteinases and metalloproteinase inhibitors in choroidal neovascular membranes.

PURPOSE: Matrix metalloproteinases (MMP) are a family of extracellular matrix degrading enzymes associated with the development of neovascularization. To investigate the possible role of these enzymes in choroidal neovascularization, the mRNA expression of MMPs and tissue inhibitors of metalloproteinases (TIMPs) were analyzed in subfoveal fibrovascular membranes from patients with age-related macular degeneration (AMD). METHODS: Surgically removed subfoveal fibrovascular membranes from five eyes were analyzed for the expression of MMP and TIMP mRNA. In situ hybridization anti-sense and sense riboprobes were generated using DNA complementary to human collagenase (MMP-1), 72 kDa gelatinase (MMP-2), stromelysin (MMP-3), 92-kDa gelatinase (MMP-9), TIMP-1, TIMP-2, and TIMP-3. Vascular endothelial cells were detected using immunostaining for von Willebrand factor. RESULTS: MMP-2 and MMP-9 mRNA were detected in all specimens. Most of the membranes also expressed TIMP-1 and TIMP-3 mRNA, and two of the membranes expressed TIMP-2 mRNA. MMP-2, TIMP-1, and TIMP-2 mRNA had a similar overall distribution that was relatively uniform within the vascularized membrane stroma. MMP-2 expression appeared to be localized mainly to the vascular endothelial cells, whereas TIMP-1 and TIMP-3 were detected in other cell types such as fibroblastlike cells. MMP-9 expression was distinctly expressed by cells at the margins of the membranes and often in proximity to a thickened Bruch's membrane-like layer under the retinal pigment epithelial cells. TIMP-3 mRNA was strongly expressed within the retinal pigment epithelial cell layer and also in the stroma of one membrane. None of the membranes showed detectable MMP-1 or MMP-3 expression. CONCLUSIONS: The results support a role for MMPs in the development of choroidal neovascularization in AMD. The localization of MMP-2 and MMP-9 to the areas of new vessel formation and to the enveloping Bruch's-like membrane, respectively, suggests that MMP-2 and MMP-9 may be cooperatively involved in the progressive growth of choroidal neovascular membranes in AMD.

Beta-amyloid protein protein precursor expression in lacrimal glands and tear fluid.

PURPOSE: Proteases in tear fluid play important roles in the regulation of corneal wound healing. Inhibitors of proteolytic activity are major modulators of the associated events. Although it is known that various enzyme inhibitors exist in tear fluid, it is not known whether certain isoforms of the beta-amyloid protein precursor (beta-APP), a potent inhibitor of serine proteases, are present in tear fluid. The purpose of this study was to investigate whether beta-APP can be detected in human tear fluid and, if so, to determine the isoform composition and cellular origin. METHODS: Tear fluid was collected from healthy volunteers. The beta-APP was identified and characterized by immunoblotting using antibodies specific for domains of the beta-APP. The protein was characterized further by ion exchange chromatography. Expression of the beta-APP gene was studied using in situ hybridization and RNA-RNA solution hybridization assay. RESULTS: beta-APP with protease inhibitory properties was identified in all samples of human tear fluid. Immunologic analysis revealed that it had been processed proteolytically before secretion. Gene expression studies showed that the beta-APP gene was expressed in lacrimal glands, particularly in acinar cells. The gene transcript almost exclusively corresponded to beta-APP containing the protease inhibitor insert. CONCLUSIONS: beta-APP is expressed in lacrimal glands and subsequently is secreted into tear fluid. Because the bulk of the beta-APP contained the protease inhibitor insert, the authors propose that beta-APP is an important regulator of proteolysis in tear fluid and that possibly it plays a role in the events associated with corneal wound healing. This suggests a novel physiological function of beta-APP in addition to those previously described-regulation of blood coagulation and cell growth.

Synergistic effects between protein kinase C and cAMP on activator protein-1 activity and differentiation of PC-12 pheochromocytoma cells.

In rat pheochromocytoma cells (PC-12) cells, we have studied the effect of protein kinase C (PKC) and cAMP on the activity of the nuclear transcription factor activator protein-1 (AP-1) and on differentiation of the cells into sympathetic nerve-like phenotype. By using mobility gel-shift assays, we found that both PKC and cAMP activation led to an increase in the binding of AP-1 to its consensus nucleotide sequence (TRE). When the PKC and cAMP pathways were activated simultaneously, a clear-cut synergistic effect was seen on the binding of AP-1 to TRE. Both PKC and cAMP activation were furthermore able to increase the AP-1 transcriptional activity in PC-12 cells transiently transfected with TRE-expressing plasmids. In agreement with the mobility gel-shift results, simultaneous activation of PKC and cAMP synergistically increased the AP-1 transcriptional activity. We next analyzed the effect of PKC and cAMP stimulation on differentiation and proliferation of PC-12 cells. Whereas PKC activation had no effect on the morphology of PC-12 cells, elevation of the intracellular cAMP level resulted in a marked increase in the number of neurite-bearing cells. This effect was paralleled by a strong inhibition of PC-12 cell proliferation. Interestingly, when PKC and cAMP activation were combined, the differentiation was further pronounced and growth further inhibited. These results show that both PKC and cAMP increase the AP-1 activity in PC-12 cells, and that these effects are synergistic. Moreover, we show that cAMP induces differentiation and inhibits growth of PC-12 cells, and that PKC activation acts synergistically with cAMP on these effects. The possible role of AP-1 in PC-12 cell differentiation is discussed.

Activation of protein kinase C and elevation of cAMP interact synergistically to raise c-Fos and AP-1 activity in Jurkat cells.

We have earlier found that in Jurkat cells activation of protein kinase C (PKC) enhances the cyclic adenosine monophosphate (cAMP) accumulation induced by adenosine receptor stimulation or activation of Gs. Here we have therefore examined the effect of the phorbol ester PMA (phorbol 12-myristate 13-acetate) which stimulates PKC and a combination of the adenosine receptor agonist NECA (5'-(N-ethyl)-carboxamido adenosine) and forskolin to raise cAMP, on the levels of c-Fos and Jun and on the binding and transcriptional activity of the transcription factor, activator protein-1 (AP-1). PMA treatment caused a concentration- and time-dependent increase in both c-Fos and Jun immunoreactivity in contrast to cAMP elevation that had only a slight effect. Both PMA and the combination of NECA and forskolin acted together either to increase (c-Fos) or decrease (Jun) protein levels as well as increasing AP-1 binding, as judged by gel-shift assay, and AP-1 transcriptional activity. Furthermore there was a clear-cut synergy between the PKC stimulator and the cAMP elevating agents. The results demonstrate that the simultaneous activation of PKC and elevation of cAMP leads to an enhanced AP-1 transcriptional activity in a T-leukemia cell line, suggesting that the previously observed interaction between the parallel signal transduction pathways may have functional consequences at the level of gene transcription.

Dual effects of protein kinase-C on receptor-stimulated cAMP accumulation in a human T-cell leukemia line.

In the human T-cell leukemia line Jurkat, cAMP accumulation stimulated by the adenosine receptor agonist 5'-N-ethylcarboxamido adenosine (NECA) was enhanced by tumour-promoting phorbol esters whereas the prostaglandin receptor-stimulated accumulation of cAMP was antagonized. Phorbol esters did not alter the adenosine or prostaglandin receptor-stimulated accumulation of cAMP in cells in which the phospholipid/Ca2+-dependent protein kinase (protein kinase-C) was down-regulated. cAMP stimulation induced by cholera toxin (CT) was enhanced by phorbol esters by 100-300%. The cAMP production induced by forskolin was never enhanced by more than 50% by 4 beta-phorbol-12,13-dibutyrate (PDBu) and there was no stimulation at all after down-regulation of the adenosine receptor by treatment with NECA. Phorbol ester enhanced the NECA-stimulated accumulation of cAMP, even in the presence of concentrations of forskolin that increased the cAMP accumulation several-fold. From these data we conclude that protein kinase-C can interact with receptors coupled to adenylate cyclase in a stimulatory as well as an inhibitory manner. Moreover, protein kinase-C appears to interact with signal transduction at two levels, one highly receptor-specific and one distal to the receptor.

Stimulation of the T-cell receptors CD3 and CD2 with OKT3 and OKT11 antibodies activates a common pertussis toxin-insensitive G-protein.

The association of G-proteins with the T-cell-specific receptor structures CD3 and CD2 was investigated. High-affinity GTPase activity in membrane preparations of the human leukemic T-cell line Jurkat could be induced by the monoclonal antibodies OKT3 (anti-CD3) and OKT11 (anti-CD2). When combining maximally active concentrations of OKT3 and OKT11, no additive effect was seen on GTPase activity. In mutant Jurkat cells lacking the CD3 complex but with an intact CD2 receptor, neither OKT3 nor OKT11 could stimulate GTPase activity. Activation of CD3 and CD2 by monoclonal antibodies also stimulated phospholipase C activity as measured by breakdown of membrane phosphoinositides in wild-type but not in mutant Jurkat cells. Neither GTPase nor phospholipase C activation was sensitive to pretreatment with doses of pertussis toxin (PTX) that caused ADP ribosylation of a sensitive G-protein. Our data show that the CD3 complex and the CD2 receptor may activate a common PTX-insensitive G-protein. The CD2 receptor appears to stimulate the G-protein by interacting with the CD3 complex. The data are compatible with, but do not prove, that this G-protein is involved in the activation of phospholipase C by the two receptors.

Activation of protein kinase C via the T-cell receptor complex potentiates cyclic AMP responses in T-cells.

We have recently shown that activation of protein kinase C by tumour promoting phorbolesters, such as 4 beta-phorbol-12,13-dibutyrate, stimulates adenosine-induced accumulation of cAMP in Jurkat cells, a human T-leukaemia line. Activating the CD3 complex associated with the T-cell receptor by means of the monoclonal antibody OKT3 caused a concentration-dependent accumulation of inositol phosphates and an increase in the phosphorylation of an endogenous protein kinase C substrate. OKT3 also mimicked the previously reported effects of protein kinase C since it potentiated the cAMP stimulation by either an adenosine analogue, NECA, or cholera toxin. Thus, our results indicate that stimulation of a receptor activating phospholipase C and protein kinase C can secondarily enhance the action of agonists that act on adenylate cyclase-coupled receptors.

Role of a pertussis toxin sensitive G-protein in mediating the effects of phorbol esters on receptor activated cyclic AMP accumulation in Jurkat cells.

In the human T-cell line, Jurkat, the accumulation of cyclic AMP induced by adenosine is enhanced by tumor-promoting phorbol esters, whereas prostaglandin E2 receptor-stimulated cAMP accumulation is antagonized (Nordstedt et al. 1989). In the present study we examine the involvement of pertussis toxin sensitive guanine nucleotide binding proteins (G-proteins) in producing the phorbol ester effects. Pertussis toxin pretreatment of the Jurkat cells invariably caused an ADP ribosylation of two G-proteins that inhibit adenylyl cyclase, tentatively identified as Gi2 and Gi3, using Western blots. Pertussis toxin treatment had little effect on basal cAMP accumulation, but sometimes inhibited, sometimes stimulated agonist and cholera toxin induced cAMP accumulation. The latter effect was not mimicked by the B-oligomer. Irrespective of whether pertussis toxin stimulated or inhibited NECA and cholera toxin-induced cAMP accumulation it could not block the effect of phorbol-12,13-dibutyrate (PDBu). The inhibitory effect of PDBu on prostaglandin E2-induced cAMP accumulation was, however, invariably eliminated by pertussis toxin treatment. In conclusion, activation of protein kinase C by phorbol esters reveals a Gi-mediated prostaglandin E receptor-induced inhibition of adenylate cyclase in addition to the prostaglandin E receptor-mediated stimulation of cAMP accumulation in Jurkat cells. The enhancement of adenosine A2 receptor stimulated cAMP accumulation by PDBu, on the other hand, does not involve a PTX sensitive Gi-protein.

Further evidence that propentofylline (HWA 285) influences both adenosine receptors and adenosine transport.

We have examined the actions of a novel xanthine derivative, propentofylline (HWA 285), that has been shown to protect against ischemic brain damage in rats and gerbils, on adenosine receptors (A1 and A2), and on adenosine transporters using several techniques, cells and tissues. Propentofylline and its hydroxylated metabolite A 72 0287 were about 20 times less potent than theophylline in displacing A1-agonist binding to membranes from rat cortex, and A1-antagonist binding to whole DDT, MF-2 smooth muscle cells. A1-agonist binding to adenosine A1-receptors in several brain structures was inhibited in a concentration-dependent manner by A 72 0287 and propentofylline as judged by quantitative autoradiography (IC50-values 300-600 microM in eg striatum and in cortex layer IV). In two functional assays, A1-receptor mediated effects were blocked by propentofylline. A1-receptor-mediated inhibition of cyclic AMP accumulation was virtually abolished by 100 microM propentofylline. The A1-receptor-mediated inhibition of evoked acetylcholine release was also reduced by propentofylline, but in this case the effect is not due exclusively to adenosine receptor antagonism but also to another action since the presynaptic inhibitory effect of carbachol was also inhibited. Adenosine A2-receptors were also antagonized by propentofylline as judged by a concentration-dependent antagonism of A2-agonist-induced cAMP accumulation in human T-leukemia cells (possessing putative A2b-receptors; pA2-value 180 microM compared to 0.26 microM for 8-cpt), and in PC-12 cells (possessing putative A2a-receptors, Ki-value 365 microM). Finally, adenosine transporters were affected by propentofylline and A 72 0287. Thus, [3H]-nitrobenzylthioinosine-binding to guinea-pig cardiac membranes was blocked by propentofylline or A 72 0287 (Ki 270 microM). The present results show that propentofylline and its hydroxylated metabolite can influence adenosine mechanisms in a multitude of ways. How these different actions may contribute to the ability of propentofylline to reduce the magnitude of ischemic damage is discussed.

Expression and regulation of vascular endothelial growth factor in choroidal fibroblasts.

Subretinal neovascularization is a severe sight-threatening complication into age-related macular degeneration. Previous immunohistochemical studies on surgically removed neovascular membranes have revealed that these membranes, in addition to the neovascular stroma, are comprised of several different cell types such as retinal pigment epithelial (RPE) cells, choroidal fibroblasts and vascular endothelial cells. Since vascular endothelial growth factor (VEGF) potently and specifically induces angiogenesis it was investigated whether VEGF is expressed and/or inducible in choroidal fibroblasts and RPE cells. Choroidal fibroblasts and RPE cells were isolated from human adult post-mortem eyes and expression of VEGF mRNA and protein was measured. By using Northern blotting, both choroidal fibroblasts and RPE cells were found to express VEGF mRNA at low levels. In order to examine whether this VEGF expression was further inducible, the intracellular effector enzyme protein kinase C was activated by phorbol esters. This activation resulted in a prominent increase in VEGF mRNA in choroidal fibroblasts, but not in RPE cells, with a maximal increase detected after 6 h. Elevation of intracellular cyclic AMP levels by forskolin had no clear effect on VEGF mRNA in either cell type. Stimulation with interleukin-1, transforming growth factor beta, tumour necrosis factor alpha and platelet derived growth factor was tested to see if VEGF expression is cytokine inducible. Both interleukin-1 and transforming growth factor beta induced VEGF expression in choroidal fibroblasts although with different time courses. Whereas the transforming growth factor beta effect was transient the interleukin-1 effect was sustained for at least 48 h. None of the cytokines tested affected VEGF expression in RPE cells. By using Western blotting, it was further found that stimulation with interleukin-1 induced VEGF protein expression in choroidal fibroblasts but not in RPE cells. In conclusion, choroidal fibroblasts respond by elevated VEGF mRNA levels after phorbol ester, interleukin-1 and transforming growth factor beta stimulation and elevated VEGF protein levels after phorbol ester and interleukin-1 stimulation suggesting that choroidal fibroblasts may be target cells for increased VEGF synthesis secondary to paracrine cytokine production.

Matrix metalloproteinase (MMP) expression in experimental choroidal neovascularization.

PURPOSE: Matrix metalloproteinases (MMP) are a family of proteolytic enzymes that degrade basement membrane and extracellular matrix proteins. To gain information on the possible role of MMPs in choroidal neovascularization (CNV), we have analyzed the mRNA expression of MMP-2 and MMP-9, two forms of MMPs implicated in ocular neovascularization, in a rat model. METHODS: Choroidal neovascularization was induced in pigmented rats by krypton laser photocoagulation of the fundus whereafter eyes were enucleated at 1, 3, 5, 7, 10 and 60 days. Antisense and sense riboprobes were generated using DNA complementary to MMP-2 and MMP-9, and mRNA expression was analyzed using in situ hybridization. RESULTS: In the untreated eyes MMP-2 mRNA expression was weakly detected in cells within the choroid. In laser-treated eyes MMP-2 mRNA expression was markedly increased and mainly localized to macrophage-like and retinal pigment epithelial (RPE)-like cells invading the choroid, subretinal space and inner retina. This increase in MMP-2 mRNA expression peaked at day 10 whereafter a decline was detected. MMP-9 mRNA expression was low in untreated eyes and did not increase following laser treatment. CONCLUSION: The results show that MMP-2 mRNA expression is increased in experimental CNV, and support of a role for MMP-2 in the development of CNV in age-related macular degeneration.

[Vascular endothelial growth factor. A vascular growth factor of high specificity]. / Vascular endothelial growth factor. En vaskulär tillväxtfaktor med hög specificitet.

Angiogenesis, the formation of new blood vessels, is regulated by angiogenic growth factor. Vascular endothelial growth factor (VEGF) is a recently discovered growth factor that, in contrast to other growth factors with angiogenic activity, acts specifically on the vascular endothelium. VEGF is involved in the induction of new blood vessel formation in various physiological and pathological processes associated with increased angiogenesis.

Diagnostic incisional biopsies in clinically indeterminate choroidal tumours.

Most intraocular tumours are reliably diagnosed by a careful clinical examination combined with one or more non-invasive diagnostic techniques. However, in a small percentage of tumours, typically small and clinically amelanotic, the features are insufficiently distinct for a confident clinical diagnosis and tissue is required for diagnosis. We used a 23-G vitreous cutter to access the biopsy site in 43 patients with clinically indeterminate tumours. After retinotomy, an incisional choroidal biopsy yielded a specimen of ∼1 mm(3). Obtained tissue was routinely processed for light microscopy including an immunohistochemical panel of monoclonal antibodies. Adequate tissue for diagnosis was provided in 41/43 (95%) patients. The sensitivity and specificity to detect malignant disease were 0.97 and 1.00, respectively. The positive predictive value was 1.00. Complications included progression of pre-existing retinal detachment in 5/43 (12%) patients and transient rise in intraocular pressure to >40 mm Hg in 6/43 (14%) patients; 4 of these 6 patients had a pre-existing retinal detachment. No patient with a pre-operatively attached retina had a retinal detachment. We conclude that an incisional transretinal choroidal biopsy yields abundant material and may adequately confirm or exclude malignancy in patients with clinically indeterminate tumours. The complication rate can be minimised when patients with pre-existing retinal detachment are excluded from biopsy.