Carl Soderland

Endothelial cells release phenotypically and quantitatively distinct microparticles in activation and apoptosis.

BACKGROUND Endothelial cells (EC) shed endothelial microparticles (EMP) in activation and apoptosis. OBJECTIVES We compared the antigenic expression of EMP species released during activation as compared to apoptosis, in three cell lines. METHODS EC from renal and brain microvascular (MiVEC) and coronary macrovascular (MaVEC) origin were incubated with TNF-alpha to induce activation, or deprived of growth factors to induce apoptosis. Antigens expressed on EMP and EC were assayed flow cytometrically and included constitutive markers (CD31, CD51/61, CD105), inducible markers (CD54, CD62E and CD106), and annexin V binding. RESULTS It was found that in apoptosis, constitutive markers in EMP were markedly increased (CD31>CD105), with a concomitant decrease in expression in EC. Annexin V EC surface binding and annexin V+ EMP were more sharply increased in apoptosis than in activation. In contrast, in activation, inducible markers in EMP were markedly increased in both EMP and EC (CD62E>CD54>CD106). Coronary MaVEC released significantly less EMP than MiVEC. CONCLUSION EC release qualitatively and quantitatively distinct EMP during activation compared to apoptosis. Analysis of EMP phenotypic signatures may provide clinically useful information on the status of the endothelium.

Endothelial microparticles released in thrombotic thrombocytopenic purpura express von Willebrand factor and markers of endothelial activation.

Summary.  It has been suggested that endothelial apoptosis is a primary lesion in the pathogenesis of thrombotic thrombocytopenic purpura (TTP). We tested this hypothesis by examining the phenotypic signatures of endothelial microparticles (EMP) in TTP patients. In addition, the effect of TTP plasma on microvascular endothelial cells (MVEC) in culture was further delineated. EMP released by endothelial cells (EC) express markers of the parent EC; EMP released in activation carry predominantly CD54 and CD62E, while those in apoptosis CD31 and CD105. We investigated EMP release in vitro and in TTP patients. Following incubation of MVEC with TTP plasma, EMP and EC were analysed by flow cytometry for the expression of CD31, CD51, CD54, CD62E, CD105, CD106 and von Willebrand factor (VWF) antigen. EMP were also analysed in 12 TTP patients. In both EC and EMP, CD62E and CD54 expression were increased 3‐ to 10‐fold and 8‐ to 10‐fold respectively. However, CD31 and CD105 were reduced 40–60% in EC but increased twofold in EMP. VWF expression was found in 55 ± 15% of CD62E+ EMP. Markers of apoptosis were negative. In TTP patients, CD62E+ and CD31+/CD42b− EMP were markedly elevated, and preceded and correlated well with a rise in platelet counts and a fall in lactate dehydrogenase. CD62E+ EMP (60 ± 20%) co‐expressed VWF and CD62E. The ratio of CD31+/42b− to CD62E+ EMP exhibited a pattern consistent with activation. In conclusion, our studies indicate endothelial activation in TTP. EMP that co‐express VWF and CD62E could play a role in the pathogenesis of TTP.

Interactions between HIV-infected monocyte-derived macrophages and human brain microvascular endothelial cells result in increased expression of CC chemokines

The presence of perivascular monocytic infiltration is a major hallmark of HIV-1-associated dementia. Since CC chemokines are chemoattractant cytokines that are able to attract T cells and monocytes/macrophages to sites of inflammation, and since infiltrating monocytes/macrophages remain in close contact with the brain endothelium, we investigated whether interactions between HIV-1-infected macrophages and brain endothelium result in an altered chemokine production. We found an increased mRNA expression of monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta, and RANTES by macrophages after HIV-1 infection. Interactions between HIV-infected macrophages and brain microvascular endothelial cells resulted in an additional upregulation of chemokine mRNA expression, during cell-cell contact as well as in a trans-well system. Since IL-1 beta can function as a modulator of chemokine expression we investigated if interleukin-1 beta could be involved in the regulation of chemokine induction. Coculturing of HIV-infected macrophages and endothelial cells resulted in immune-activation as indicated by increased mRNA expression of IL-1 beta. Subsequently, addition of a neutralizing antibody against IL-1 beta resulted in altered chemokine expression by macrophages, but not by endothelial cells. Thus, IL-1 beta appears to play a major role in the regulation of chemokines during cellular interactions in HIV-associated dementia, but other factors may also be involved.

Human Endometrial Endothelial Cells: Isolation, Characterization, and Inflammatory-Mediated Expression of Tissue Factor and Type 1 Plasminogen Activator Inhibitor

Abstract Binding of Ulex europaeus lectin to microvessels was used to isolate endothelial cells from cycling human endometrium. Cultured human endometrial endothelial cells (HEECs) exhibited endothelial cell-specific characteristics such as tube formation on a basement membrane matrix and sequestration of acetylated low-density lipoprotein. Markers for potentially contaminating epithelial, stromal, smooth muscle, and bone marrow-derived cells were not detected in the HEEC cultures. Basal and proinflammatory-stimulated immunostaining profiles for endothelial cell-specific adhesion markers, as exemplified by Von Willebrands factor and E-selectin, were similar for cultured HEECs and human umbilical venous cord endothelial cells (HUVECs). However, HUVECs expressed several extracellular matrix proteins that were absent from cultured HEECs. In the latter, the protein kinase C agonist phorbol myristate acetate transiently enhanced tissue factor (TF) mRNA levels and elicited a more prolonged elevation in TF protein levels, but did not affect plasminogen activator inhibitor-1 (PAI-1) mRNA and protein levels. Inappropriate expression of TF, which initiates hemostasis by generating thrombin, and of PAI-1, which regulates hemostasis by acting as the primary inhibitor of fibrinolysis, can each lead to thrombosis. The differential regulation of TF and PAI-1 expression revealed in the current study emphasizes the importance of using HEECs to evaluate mechanisms regulating the hemostatic/thrombotic balance in human endometrium.

Compound 49b Prevents Diabetes-Induced Apoptosis through Increased IGFBP-3 Levels

PURPOSE To determine whether Compound 49b, a novel PKA-activating drug, can prevent diabetic-like changes in the rat retina through increased insulin-like growth factor binding protein-3 (IGFBP-3) levels. METHODS For the cell culture studies, we used both human retinal endothelial cells (REC) and retinal Müller cells in either 5 mM (normal) or 25 mM (high) glucose. Cells were treated with 50 nM Compound 49b alone of following treatment with protein kinase A (PKA) siRNA or IGFBP-3 siRNA. Western blotting and ELISA analyses were done to verify PKA and IGFBP-3 knockdown, as well as to measure apoptotic markers. For animal studies, we used streptozotocin-treated rats after 2 and 8 months of diabetes. Some rats were treated topically with 1 mM Compound 49b. Analyses were done for retinal thickness, cell numbers in the ganglion cell layer, pericyte ghosts, and numbers of degenerate capillaries, as well as electroretinogram and heart morphology. RESULTS Compound 49b requires active PKA and IGFBP-3 to prevent apoptosis of REC. Compound 49b significantly reduced the numbers of degenerate capillaries and pericyte ghosts, while preventing the decreased retinal thickness and loss of cells in the ganglion cell layer. Compound 49b maintained a normal electroretinogram, with no changes in blood pressure, intraocular pressure, or heart morphological changes. CONCLUSIONS Topical Compound 49b is able to prevent diabetic-like changes in the rat retina, without producing systemic changes. Compound 49b is able to prevent REC apoptosis through increasing IGFBP-3 levels, which are reduced in response to hyperglycemia.

TNFα and SOCS3 regulate IRS-1 to increase retinal endothelial cell apoptosis

Rates of diabetes are reaching epidemic levels. The key problem in both type 1 and type 2 diabetes is dysfunctional insulin signaling, either due to lack of production or due to impaired insulin sensitivity. A key feature of diabetic retinopathy in animal models is degenerate capillary formation. The goal of this present study was to investigate a potential mechanism for retinal endothelial cell apoptosis in response to hyperglycemia. The hypothesis was that hyperglycemia-induced TNFα leads to retinal endothelial cell apoptosis through inhibition of insulin signaling. To test the hypothesis, primary human retinal endothelial cells were grown in normal glucose (5 mM) or high glucose (25 mM) and treated with exogenous TNFα, TNFα siRNA or suppressor of cytokine signaling 3 (SOCS3) siRNA. Cell lysates were processed for Western blotting and ELISA analyses to verify TNFα and SOCS3 knockdown, as well as key pro- and anti-apoptotic factors, IRS-1, and Akt. Data indicate that high glucose culturing conditions significantly increase TNFα and SOCS3 protein levels. Knockdown of TNFα and SOCS3 significantly increases anti-apoptotic proteins, while decreasing pro-apoptotic proteins. Knockdown of TNFα leads to decreased phosphorylation of IRS-1(Ser307), which would promote normal insulin signaling. Knockdown of SOCS3 increased total IRS-1 levels, as well as decreased IR(Tyr960), both of which would inhibit retinal endothelial cell apoptosis through increased insulin signaling. Taken together, our findings suggest that increased TNFα inhibits insulin signaling in 2 ways: 1) increased phosphorylation of IRS-1(Ser307), 2) increased SOCS3 levels to decrease total IRS-1 and increase IR(Tyr960), both of which block normal insulin signal transduction. Resolution of the hyperglycemia-induced TNFα levels in retinal endothelial cells may prevent apoptosis through disinhibition of insulin receptor signaling.

Induction of HLA mutations by chemical mutagens in human lymphoid cells

We studied the effects of mutagens on the frequency of HLA “loss” variants in the diploid human lymphoid cell line T5-1, as well as the stability of mutagen-induced variants and the extent of the genetic lesions induced. Mutagens used were of different types, and included ethyl methanesulfonate (EMS), ICR-191 (ICR), and mitomycin C. Variant frequency was determined seven days after a 24-hour exposure to mutagen, by which time the cloning efficiency of exposed cultures, which was reduced following mutagenesis, had returned to normal. ICR and EMS induced dose-related increases in variant frequency of greater than two orders of magnitude at the highest concentrations tested. Mitomycin C increased variant frequency by tenfold at the one concentration tested. Seventeen of 18 induced variants showed persistence of the variant phenotype during prolonged culture following isolation. Genetic lesions induced by ICR and EMS did not extend as far as the distance between theHLA-A and -B loci (0.8 map units) in any of 21 clones tested. These data suggest a mutational origin for most mutagen-induced HLA variants of diploid cells (except for some induced by mitomycin C). Mutagenesis and mutational analysis are promising probes for studies of theHLA region.

Sporadic late onset nemaline myopathy responsive to IVIg and immunotherapy

Sporadic late onset nemaline myopathy (SLONM) is a progressive myopathy of indeterminate etiology and poor outcome. If associated with a monoclonal gammopathy, SLONM carries a more unfavorable prognosis. Immunotherapy was unsuccessful. We report two HIV‐negative SLONM/monoclonal gammopathy patients who improved following intravenous immunoglobulin (IVIg) treatment alone or in combination with immunosuppressant agents. This favorable response to treatment suggests that a dysimmune mechanism is operative in some SLONM individuals. We suggest that IVIg deserves initial consideration for SLONM therapy. Muscle Nerve, 2010

Intra-ophthalmic artery chemotherapy triggers vascular toxicity through endothelial cell inflammation and leukostasis.

Purpose. Super-selective intra-ophthalmic artery chemotherapy (SSIOAC) is an eye-targeted drug-delivery strategy to treat retinoblastoma, the most prevalent primary ocular malignancy in children. Unfortunately, recent clinical reports associate adverse vascular toxicities with SSIOAC using melphalan, the most commonly used chemotherapeutic. Methods. To explore reasons for the unexpected vascular toxicities, we examined the effects of melphalan, as well as carboplatin (another chemotherapeutic used with retinoblastoma), in vitro using primary human retinal endothelial cells, and in vivo using a non-human primate model, which allowed us to monitor the retina in real time during SSIOAC. Results. Both melphalan and carboplatin triggered human retinal endothelial cell migration, proliferation, apoptosis, and increased expression of adhesion proteins intracellullar adhesion molecule-1 [ICAM-1] and soluble chemotactic factors (IL-8). Melphalan increased monocytic adhesion to human retinal endothelial cells. Consistent with these in vitro findings, histopathology showed vessel wall endothelial cell changes, leukostasis, and vessel occlusion. Conclusions. These results reflect a direct interaction of chemotherapeutic drugs with both the vascular endothelium and monocytes. The vascular toxicity may be related to the pH, the pulsatile delivery, or the chemotherapeutic drugs used. Our long-term goal is to determine if changes in the drug of choice and/or delivery procedures will decrease vascular toxicity and lead to better eye-targeted treatment strategies.

IGFBP-3 and TNF-α regulate retinal endothelial cell apoptosis.

PURPOSE We hypothesized that loss of insulin-like growth factor binding protein 3 (IGFBP-3) signaling would produce neuronal changes in the retina similar to early diabetes. METHODS To understand better the role of IGFBP-3 in the retina, IGFBP-3 knockout (KO) mice were evaluated for neuronal, vascular, and functional changes compared to wild-type littermates. We also cultured retinal endothelial cells (REC) in normoglycemia or hyperglycemia to determine the interaction between IGFBP-3 and TNF-α, as data indicate that both proteins are regulated by β-adrenergic receptors and respond antagonistically. We also treated some cells with Compound 49b, a novel β-adrenergic receptor agonist we have reported previously to regulate IGFBP-3 and TNF-α. RESULTS Electroretinogram analyses showed decreased B-wave and oscillatory potential amplitudes in the IGFBP-3 KO mice, corresponding to increased apoptosis. Retinal thickness and cell numbers in the ganglion cell layer were reduced in the IGFBP-3 KO mice. As expected, loss of IGFBP-3 was associated with increased TNF-α levels. When TNF-α and IGFBP-3 were applied to REC, they worked antagonistically, with IGFBP-3 inhibiting apoptosis and TNF-α promoting apoptosis. Due to their antagonistic nature, results suggest that apoptosis of REC may depend upon which protein (IGFBP-3 versus TNF-α) is active. CONCLUSIONS Taken together, loss of IGFBP-3 signaling results in a phenotype similar to neuronal changes observed in diabetic retinopathy in the early phases, including increased TNF-α levels.