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J G Levy

Publications and source records attributed to J G Levy.

At least 37 records · Page 2Linked to original sources
PubMed1997

Inhibition of contact hypersensitivity with different analogs of benzoporphyrin derivative.

Four structural analogs of benzoporphyrin derivative (BPD), a potent anti-tumor photosensitizer, were evaluated for their capacity to influence the immunologically-mediated contact hypersensitivity (CHS) response against the hapten 2,4-dinitrofluorobenzene (DNFB). Immunocompetent hairless strain mice received BPD monoacid ring A (BPD-MA, verteporfin) and returned to normal housing conditions or treated with 690 nm red light (transcutaneous photodynamic therapy, PDT). Unexpectedly, we found that mice given BPD-MA exhibited significantly reduced CHS ear swelling responses to DNFB upon antigenic challenge, whether or not they had been treated with PDT. A significant reduction in the CHS response to DNFB was observed when BPD-MA or PDT was given 48 or 24 h prior to, on the same day, or 24 or 72 h after DNFB sensitization. However, the magnitude of the CHS response was unaffected if these treatments were given 96 h after DNFB sensitization, 24 h before challenge with DNFB. Significantly reduced CHS responses also occurred in Balb/c mice given BPD-MA with or without PDT. Mice given BPD-MA but retained in total darkness throughout the experimental period generated full-fledged ear swelling responses to DNFB indicating that CHS suppression with BPD-MA was light dependent. BPD monoacid ring B (BPD-MB) strongly reduced the CHS response of Balb/c mice kept under ambient light while BPD diacid ring A (BPD-DA) and BPD diacid ring B (BPD-DB) also lowered the CHS response but were less effective than the monoacid forms. Other photosensitizers including Photofrin, tin etiopurpurin, and zinc phthalocyanine did not alter the CHS response of Balb/c mice maintained under ambient light. The ability of different BPD analogs to inhibit the CHS response in mice held under ambient light conditions appears related to the potent photosensitizing activity of these compounds.

Adjuvants, Immunologic↗
PubMed1997

Photodynamic therapy induces caspase-3 activation in HL-60 cells.

Caspases have been shown to play a crucial role in apoptosis induced by various deleterious and physiologic stimuli. In this study, we show for the first time that photodynamic therapy (PDT), using benzoporphyrin derivative monoacid ring A (BPD-MA, verteporfin) as the photosensitizer, induces the complete cleavage and subsequent activation of caspase-3 (CPP32/Yama/Apopain) but not caspase-1 (ICE) in human promyelocytic leukemia HL-60 cells. Poly(ADP-ribose) polymerase (PARP) and the catalytic subunit of DNA dependent protein kinase (DNA PK(CS)) were cleaved within 60 min of light activation of BPD-MA. The general caspase inhibitor Z-Asp-2,6 dichlorobenzoyloxymethylketone (Z-Asp-DCB) blocked PARP cleavage while the serine protease inhibitors 3,4-dichloroisocoumarin (DCI) and N-tosyl-lysyl chloromethyl ketone (TLCK) blocked the cleavage of caspase-3 suggesting that they act upstream of caspase-3 activation. All three inhibitors were able to block DNA fragmentation that was induced by treatment with BPD-MA followed by light application. These studies demonstrate that protease activity, particularly that of caspase-3, is triggered in HL-60 cells treated with lethal levels of BPD-MA and visible light.

Journal Article↗
PubMed1997

Delivery of benzoporphyrin derivative, a photosensitizer, into atherosclerotic plaque of Watanabe heritable hyperlipidemic rabbits and balloon-injured New Zealand rabbits.

In this study we compared the plasma distribution and arterial accumulation of a photosensitizer, benzoporphyrin derivative (BPD), in two models of atherosclerosis: the spontaneous lesions of the Watanabe heritable hyperlipidemic (WHHL) rabbit and induced lesions of the balloon-injured, cholesterol-fed New Zealand white (NZW) rabbit. Selective uptake and retention of a photosensitizer by the abnormal portion of a vessel is a necessity in order for photodynamic therapy to become a successful modality for inhibition of intimal hyperplasia, selective removal of atherosclerotic tissue or imaging of diseased arteries. Liposome-based formulations were compared to freshly isolated native low density lipoprotein (LDL) and acetylated-LDL (Ac-LDL) as delivery vehicles for BPD. Plasma distribution of the photosensitizer was analyzed by KBr density gradient ultracentrifugation. Although the delivery vehicle influenced plasma distribution immediately postinjection, BPD subsequently partitioned according to the plasma concentration of the lipoproteins. Photosensitizer level in plaque and normal artery specimens was determined by ethyl acetate extraction and spectrofluorometric measurement. The measurement of BPD in normal and atherosclerotic arterial tissue demonstrated a selective accumulation in atherosclerotic tissue. Preassociation with LDL and Ac-LDL enhanced accumulation of BPD in atherosclerotic tissue when compared with normal artery (mean ratios of 2.8 and 4.1 were achieved, respectively). These results indicate that the preferential uptake of BPD by atherosclerotic plaque can be enhanced by preassociation with plasma lipoproteins, suggesting that light activation could lead to a highly selective destruction of diseased vascular tissue.

Angioplasty↗
PubMed1997

Influence of Photofrin on the hematopoietic accessory function of murine peritoneal cells.

The porphyrin photochemotherapeutic agent Photofrin stimulates hematopoietic activity within the bone marrow (BM) and spleens of normal mice. We found that the intraperitoneal (i.p.) administration of Photofrin also caused a 3-4 fold increase in peritoneal cell (PC) numbers, particularly cells bearing granulocyte surface antigens. Little granulocyte-macrophage progenitor activity was detectable within the PC population of control and Photofrin-injected mice suggesting that Photofrin had elicited an influx of inflammatory cells into the region. In contrast to cells from control animals, PC obtained 6 h to 168 h after the i.p. injection of Photofrin exhibited a consistently inferior capacity to support the growth of BM colony forming units granulocyte-macrophage (CFU-GM). When PC from control or Photofrin-treated mice were added to the BM culture system in the presence of defined growth factors there was no effect on the number of colonies formed. This finding indicated that negative regulatory elements were not responsible for the reduced hematopoietic accessory activity exhibited by PC from Photofrin-treated mice. Supernatants conditioned by PC from Photofrin-injected mice poorly supported BM CFU-GM growth in vitro and in contrast to PC supernatants prepared from control mice did not contain detectable amounts of granulocyte-macrophage colony stimulating factor (GM-CSF). The cellular changes which occur within the peritoneal cavity represent bystander events not directly related to the hematostimulatory action of Photofrin.

Animals↗
PubMed1996

Stimulation of stress-activated protein kinase and p38 HOG1 kinase in murine keratinocytes following photodynamic therapy with benzoporphyrin derivative.

The activation state of the members of the mitogen-activated protein kinase family following photodynamic therapy (PDT) with benzoporphyrin derivative monoacid ring A was investigated using a naturally transformed murine keratinocyte cell line, Pam 212. PDT involves the use of photosensitizer molecules and a specific wavelength of visible light. The process of PDT generates singlet oxygen and other reactive oxygen intermediates (ROIs), and the cytotoxic effect of these ROIs is the basis for the use of PDT to treat cancer and psoriasis. PDT caused a strong dose- and time-dependent activation of both stress-activated protein kinase (SAPK) and p38 HOG1. The maximum activation of SAPK and p38 HOG1 occurred between 20 and 30 min following PDT treatment with 200 ng/ml benzoporphyrin derivative monoacid ring A and 2 J/cm2 of red light at 690 nm. In our system, PDT did not cause significant activation of extracellularly regulated kinase (ERK) 1 and ERK2. Under the same experimental conditions, ultraviolet light irradiation caused strong activation of SAPK and p38 HOG1 and minimum activation of ERK1 and ERK2 in Pam212 cells. A number of ROI scavengers were tested for their effect on PDT-induced SAPK and p38 HOG1 activation. Both L-histidine and N-acetyl-L-cysteine showed a significant inhibitory effect on PDT-induced SAPK and p38 HOG1 activation. This indicated that PDT-induced SAPK and p38 HOG1 activation may be partially mediated by ROI.

Animals↗
PubMed1996

Photosensitizing potencies of the structural analogues of benzoporphyrin derivative in different biological test systems.

Benzoporphyrin derivative (BPD) is a potent photosensitizer in biological systems. There are four structural analogues of BPD. The analogues share the same chromophor, which results in their having almost identical optical spectra, extinction coefficients, and yields of singlet oxygen. Small structural differences affect their photosensitizing potency in various biological systems, and thus make them an interesting tool to study the structure-activity relationship. The ranking of the photosensitizing potency of the analogues differed depending on the test system. The more efficient photosensitization of tumor cell lines by the highly lipophilic monoacids as compared to that by less lipophilic diacids correlated positively with the partition coefficient, and was related to the rate of diffusion into the cells. However, in the assay systems where PDT targets were located in the membrane (red blood cells hemolysis, enveloped vesicular stomatitis virus, isolated mitochondria) there was very little difference in photosensitizing potency of BPD analogues. The results indicate that the evaluation of photosensitizers is affected by the test system and thus for photosensitizers screening purposes, the choice of the test system should be made based on the intended ultimate use.

Animals↗
PubMed1996

New applications in photodynamic therapy. Introduction.

Photodynamic therapy is now recognized as a legitimate therapy for both palliative and potentially curative treatment of solid tumors. This represents a major achievement for investigators who have committed their careers to PDT. Scientific research characteristically runs well ahead of accepted views and technologies. This Symposium-in-Print perhaps provides a snapshot of the potential for this technology during the next two decades.

Animals↗
PubMed1996

Transcutaneous photodynamic therapy alters the development of an adoptively transferred form of murine experimental autoimmune encephalomyelitis.

Transcutaneous photodynamic therapy (PDT), utilizing benzoporphyrin derivative monoacid ring A (BPD, verteporfin) and whole-body light exposure, was assessed for its capacity to modify the course of adoptively transferred experimental autoimmune encephalomyelitis (EAE) in PL mice. Using a novel cell culture technique to facilitate the induction of this neurodegenerative condition, disease signs commenced 3-4 weeks after the transfer of myelin basic protein (MBP)-reactive lymph node or spleen cells to naive syngeneic recipients. Mice administered MBP-sensitized lymph node cells preincubated with BPD followed by whole-body 690 nm light irradiation (15 J/cm2) did not display symptoms of EAE. Although almost all animals given MBP-sensitized spleen cells developed EAE, mice given BPD (1 mg/kg) and the light treatment 24, 48 or 120 h after spleen cell transfer exhibited significantly less severe disease symptoms than control animals. Mice given the photodynamic treatment 24 h after spleen cell transfer also exhibited a significantly later disease onset than the control animals. Treatment of mice with PDT 24 h prior to spleen cell transfer did not influence subsequent disease severity but modestly delayed its onset. In the absence of directed light, BPD did not influence the development of EAE. Spinal cord tissues were evaluated for the presence of T cell receptor (TCR) V alpha 4 mRNA transcripts that specifically encode for the TCR alpha-chain of MBP-reactive T cells of PL mice. Using the polymerase chain reaction, V alpha 4 TCR mRNA transcripts were present in spinal cord samples prepared from almost all control mice but in only about one-half of spinal cord samples prepared from mice treated with PDT 24 h after spleen cell transfer. These observations indicated that PDT had limited the expansion of MBP-specific V alpha 4+ T cells within the central nervous system. Transcutaneous PDT represents a new technique with which to approach the treatment of autoimmune disease.

Animals↗
PubMed1996

Monoclonal antibody LR-1 recognizes murine heat-stable antigen, a marker of antigen-presenting cells and developing hematopoietic cells.

The rat monoclonal antibody LR-1 was initially described to be reactive with an antigen present on murine splenic B lymphocytes. However, flow-cytometric analyses of cells obtained from thymus, bone marrow, spleen, and lymph nodes showed that LR-1 stained approximately 95, 95, 60-70 and 20% of cells present within these tissues in normal DBA/2 mice. The marker recognized by LR-1 was present on peripheral erythrocytes and splenic dendritic cells, and activation with lipopolysaccharide A further increased expression of this antigen by splenic B cells. This particular tissue and cellular distribution was similar to that delineated with monoclonal antibodies reactive with heat-stable antigen (HSA). Duallabelling studies were conducted to compare the reactivity patterns of LR-1 and the HSA-reactive monoclonal antibody J11d and indicated that both antibodies recognized splenocytes bearing B cell (IgM) or erythroid (TER-119, CD71) but not T cell (CD4, CD8) markers. Splenocytes exposed to phosphoinostol-specific phospholipase C showed marked reduction in LR-1 binding, indicating that this antibody recognized a glycosylphosphatidylinositol-anchored cell surface protein, consistent with the known structure of HSA. Mixing of LR-1 with the HSA-specific antibodies J11d or M1/69 provided flow-cytometric profiles indistinguishable from those obtained with either antibody alone. However, LR-1 inhibited M1/69 binding to splenocytes by 83%, while J11d reduced M1/69 binding to these cells by only 18%. This finding suggested that LR-1 and M1/69 recognize identical splenic HSA epitopes, while LR-1 and J11d bind distinct antigenic determinants of spleen HSA. Western blot analysis of splenocyte, thymocyte, bone marrow cell and erythrocyte detergent extracts revealed that LR-1 reacted with glycoforms of HSA of known molecular weights (30-55 kD). Thus, LR-1 recognizes HSA, the murine analogue of human CD24, and will be a useful reagent with which to investigate the role of HSA in the immune response and hematopoiesis.

Animals↗
PubMed1995

Selective elimination of malignant stem cells using photosensitizers followed by light treatment.

The pros and cons of purging of either bone marrow or peripheral blood stem cell preparations for autologous transplantation for cancer has been debated strongly over the past decade. Recent data implicating the role of minimal residual disease in autografted marrow in cancer relapse have renewed interest in this question. There is a considerable body of literature supporting the possibility that photosensitizer molecules in combination with light might provide a therapeutic window permitting selective elimination of malignant stem cells while sparing those of normal lineage. Molecules of this class are known to be taken up more actively by most malignant cells, and intracellular concentrations are critical in their cytotoxic effect when they are activated by light at an appropriate wavelength. The present paper reviews the observations made over the past decade on a variety of photosensitizers and their effects on hemopoietic progenitors.

Bone Marrow Purging↗
PubMed1995

Accelerated myelopoietic recovery in irradiated mice treated with Photofrin.

The porphyrin photosensitizer, Photofrin porfimer sodium (Photofrin), has been widely studied for its capacity to evoke destruction of malignant tissues. In addition to its photosensitizing properties, Photofrin may exert myelostimulatory effects in normal and immunosuppressed mice in the absence of activating light. In the present set of experiments, we examined the effect of Photofrin upon the immunohematopoietic axis of sublethally irradiated DBA/2 mice. Administration of Photofrin (10 mg/kg) 1 and 4 days following irradiation (4 Gy) significantly enhanced the recovery of spleen cellularity, spleen and bone granulocyte/macrophage progenitors (colony-forming units, CFU-GM) and peripheral blood leukocytes levels. Proliferative responses to the T-cell mitogen concanavalin A by spleen cells prepared from Photofrin-treated mice were significantly less than those of cells from irradiated control mice 8 and 15 days post-irradiation. Photofrin given 1, 4 and 7 days following irradiation elevated splenic CFU-GM 3 to 4-fold 10 days post-irradiation relative to the irradiated controls and mice given only two injections of Photofrin. In contrast to the effect of two injections, multiple (three or four) injections of Photofrin did not elevate bone marrow CFU-GM above control levels beyond 8 days post-irradiation. In addition, splenic CFU-GM levels in animals receiving three or four injections of Photofrin were no different than those of the irradiated controls later than 10 days post-irradiation. These findings indicate that prolonged exposure to Photofrin in sublethally irradiated mice may induce regulatory factors which dampen the enhanced myelopoietic recovery stimulated by only two injections of the drug.

Animals↗
PubMed1995

Photodynamic therapy.

Photodynamic therapy (PDT) involves the use of a class of molecules that are activated by light, and which accumulate in, and are retained by, certain abnormal tissues. When these molecules (known as photosensitizers) are activated by light, they cause the formation of active forms of oxygen, which result in the killing of cells in which the photosensitizers are present. Thus, PDT can be used to destroy diseased areas of tissue selectively, while sparing the normal surrounding tissue. PDT has been extensively studied in the treatment of cancer, but the technology has potential as a treatment in a number of other disease conditions.

Dihematoporphyrin Ether↗
PubMed1995

Targeting activated lymphocytes with photodynamic therapy: susceptibility of mitogen-stimulated splenic lymphocytes to benzoporphyrin derivative (BPD) photosensitization.

Benzoporphyrin derivative monoacid ring A (BPD), a hydrophobic chlorin-like porphyrin derivative, which fluoresces strongly at 690 nm, may have potential for both oncologic and nononcologic applications in photodynamic therapy (PDT). To study the influence of cellular characteristics on the uptake of BPD, the murine tumor cell line (P815), and in vitro and in vivo concanavalin A (Con A) -stimulated and unstimulated murine splenic lymphocytes were incubated with 2 micrograms/mL BPD at 37 degrees C for 0-60 min. At various times, cells were lysed and the amount of BPD taken up by cells was quantified by fluorescence measurements. The subsets of cells taking up BPD were analyzed using a panel of monoclonal antibodies and the Coulter XL fluorescence-activated cell sorter. Furthermore, Con A-stimulated and unstimulated spleen cells were incubated with 0-50 ng/mliter of BPD for 1 h prior to exposure to red light (7.2 J/cm2). Cell survival 24 h post-PDT was measured by the MTT assay. We found that the rapidly dividing tumor cell line and mitogen-stimulated murine T cells (mainly CD4+/IL-2R+) took up significantly more BPD (5-10-fold) than do unstimulated splenic lymphocytes. Increased BPD uptake correlated with greater photoinactivation when these cells were exposed to light at a wavelength of 690 nm. These findings suggest that activated cells of the immune system may be a target for photoinactivation by BPD.

Animals↗
PubMed1995

Sensitivity of activated murine peritoneal macrophages to photodynamic killing with benzoporphyrin derivative.

This study compared the ability of highly purified resting and activated DBA/2 mouse peritoneal macrophages to survive treatment with the photosensitizer benzoporphyrin derivative (BPD, verteporfin) and light. Culture of macrophages with recombinant murine interferon-gamma (rIFN-gamma, 100 U/mL) for 72 h imparted a phenotypic and functional activation by dramatically increasing cell surface expression of major histocompatibility complex Class II (Ia) molecules and the formation of nitric oxide. The rIFN-gamma-activated macrophages were significantly (P < 0.05) more sensitive (lethal dose to cause a 50% reduction in cell survival, LD50 = 14.4 +/- 1.1 ng/mL) to photodynamic killing with BPD and light (10 J/cm2) than cells (LD50 = 18.2 +/- 2.0 ng/mL) cultured in medium alone. In contrast, macrophages treated with different concentrations of bacterial lipopolysaccharide (LPS) were as resistant or more resistant to photodynamic killing than cells cultured in medium alone. No cytotoxic effect of BPD was detected in cultures containing the drug but protected from light. Comparable amounts of BPD were taken up in vitro by unactivated and rIFN-gamma-activated macrophages, as detected by flow cytometric analysis. However, cells cultured with LPS (10 micrograms/mL) took up more BPD than macrophages cultured in medium alone or with rIFN-gamma. The DBA/2 P815 mastocytoma cells took up greater amounts of the drug and were subsequently more vulnerable to treatment with BPD and light (LD50 = 6.9 ng/mL) than macrophages cultured under any condition. The explanation for the increased vulnerability of rIFN-gamma-activated macrophages and the greater resistance of LPS-activated macrophages, relative to medium-cultured macrophages, to photodynamic killing with BPD is uncertain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The use of transcutaneous photodynamic therapy in the prevention of adjuvant-enhanced arthritis in MRL/lpr mice.

The use of transcutaneous photodynamic therapy (PDT) has been investigated in the prevention of adjuvant enhanced arthritis in MRL/lpr mice. Mice receiving adjuvant were treated with PDT at 10-day intervals starting on the day of adjuvant administration. PDT was carried out by intravenous injection of the photosensitizer, benzoporphyrin derivative-monoacid ring A, followed by its transcutaneous activation with light. Adjuvant-injected animals displayed a delayed onset and reduced incidence and severity of arthritis when compared to untreated animals. Most importantly, inflammatory structural damage to cartilage and bone tissues was prevented by PDT. PDT was found to have no adverse effects on animals as assessed by mitogen responses, hematopoiesis, and serum enzyme levels. As mitogen-activated MRL/lpr splenocytes were shown to be more susceptible to in vitro photodynamic treatment, it is postulated that the observed effects were the result of selective destruction of adjuvant-activated lymphocytes in the circulation and/or joints.

Administration, Cutaneous↗
PubMed1994

Evidence for low-density lipoprotein receptor-mediated uptake of benzoporphyrin derivative.

Plasma lipoproteins, such as low-density lipoprotein (LDL), have been proposed to enhance the delivery of hydrophobic photosensitisers to malignant tissue since tumour cells have been shown to have increased numbers of LDL receptors. We have investigated the role of this receptor in the cellular accumulation of the photosensitiser benzoporphyrin derivative (BPD). We observed that: (1) [14C]BPD-LDL accumulation by LDL receptor-negative fibroblast cell lines was insignificant compared with normal cell lines; (2) there was no evidence that BPD dissociated from LDL during incubation with the cells; and (3) chemical acetylation of LDL markedly decreased the uptake of [14C]BPD-LDL. We conclude, therefore, that virtually all of the photosensitiser accumulated by the cells was due to specific binding and internalisation via the LDL receptor. Subsequent in vivo studies in M-1 (methylcholanthrene-induced rhabdomyosarcoma) tumour-bearing DBA/2J mice showed that tumour accumulation of BPD associated with native LDL was significantly (P < 0.01) enhanced over that of acetyl-LDL-associated BPD. These results indicate that the LDL receptor is responsible for the accumulation of LDL-associated BPD both in vitro and in vivo. Thus, utilisation of this delivery system may provide for improvements in photodynamic therapy in clinical practice.

Acetylation↗
PubMed1994

Evaluation of a model for post-partum arthritis and the role of oestrogen in prevention of MRL-lpr associated rheumatic conditions.

Sixty-eight percent of female MRL-lpr mice developed a post-partum exacerbation of their mild spontaneous arthritis within 30 days of parturition. The flare became evident between 5 and 15 days after delivery. Histologically it was characterized by a significant increase of subsynovial inflammation and synovial hyperplasia without changes in the level of cartilage and bone erosion. Immunohistologically, marked subsynovial and frequent synovial staining of MHC class II bearing cells was noted, along with the sporadic presence of CD3, CD4, and CD43 receptor-bearing cells in the subsynovium. Injection of physiological levels (0.08 mg/kg) of estradiol on days 2, 3, 9, 15 and 20 post-partum delayed and reduced the flare to 23% of the animals. Administration of pharmacological amounts (0.4 mg/kg per day for 2 weeks following Freund's complete adjuvant injection) prevented adjuvant-enhanced arthritis, reducing the incidence from 67% to the baseline 21% level. Deleterious changes in the underlying systemic lupus erythematosus (SLE), as demonstrated by proteinuria and mortality rate increases, were elicited only by the employed pharmacological amounts of estradiol. These results indicate that the MRL-lpr mice might serve as a model for post-partum flare of arthritis in SLE and rheumatoid arthritis by providing an approach to study the complexity of the effects of pregnancy on autoimmune diseases, and to obtain further evidence for the involvement of oestrogen in arthritis.

Animals↗