Regulation of tumour cell sensitivity to TNF-induced oxidative stress and cytotoxicity: role of glutathione

Targeting Tumor Necrosis Factor Alpha to Mitigate Lung Injury Induced by Mustard Vesicants and Radiation

Pulmonary injury induced by mustard vesicants and radiation is characterized by DNA damage, oxidative stress, and inflammation. This is associated with increases in levels of inflammatory mediators, including tumor necrosis factor (TNF)α in the lung and upregulation of its receptor TNFR1. Dysregulated production of TNFα and TNFα signaling has been implicated in lung injury, oxidative and nitrosative stress, apoptosis, and necrosis, which contribute to tissue damage, chronic inflammation, airway hyperresponsiveness, and tissue remodeling. These findings suggest that targeting production of TNFα or TNFα activity may represent an efficacious approach to mitigating lung toxicity induced by both mustards and radiation. This review summarizes current knowledge on the role of TNFα in pathologies associated with exposure to mustard vesicants and radiation, with a focus on the therapeutic potential of TNFα-targeting agents in reducing acute injury and chronic disease pathogenesis.

Pulmonary injury and oxidative stress in rats induced by inhaled sulfur mustard is ameliorated by anti-tumor necrosis factor-α antibody

Sulfur mustard (SM) is a bifunctional alkylating agent that causes severe injury to the respiratory tract. This is accompanied by an accumulation of macrophages in the lung and the release of the proinflammatory cytokine, tumor necrosis factor (TNF)α. In these studies, we analyzed the effects of blocking TNFα on lung injury, inflammation and oxidative stress induced by inhaled SM. Rats were treated with SM vapor (0.4 mg/kg) or air control by intratracheal inhalation. This was followed 15-30 min later by anti-TNFα antibody (15mg/kg, i.v.) or PBS control. Animals were euthanized 3 days later. Anti-TNFα antibody was found to blunt SM-induced peribronchial edema, perivascular inflammation and alveolar plasma protein and inflammatory cell accumulation in the lung; this was associated with reduced expression of PCNA in histologic sections and decreases in BAL levels of fibrinogen. SM-induced increases in inflammatory proteins including soluble receptor for glycation end products, its ligand, high mobility group box-1, and matrix metalloproteinase-9 were also reduced by anti-TNFα antibody administration, along with increases in numbers of lung macrophages expressing TNFα, cyclooxygenase-2 and inducible nitric oxide synthase. This was correlated with reduced oxidative stress as measured by expression of heme oxygenase-1 and Ym-1. Together, these data suggest that inhibiting TNFα may represent an efficacious approach to mitigating acute lung injury, inflammatory macrophage activation, and oxidative stress induced by inhaled sulfur mustard.

The functions and regulation of heat shock proteins; key orchestrators of proteostasis and the heat shock response

Cells respond to protein-damaging (proteotoxic) stress by activation of the Heat Shock Response (HSR). The HSR provides cells with an enhanced ability to endure proteotoxic insults and plays a crucial role in determining subsequent cell death or survival. The HSR is, therefore, a critical factor that influences the toxicity of protein stress. While named for its vital role in the cellular response to heat stress, various components of the HSR system and the molecular chaperone network execute essential physiological functions as well as responses to other diverse toxic insults. The effector molecules of the HSR, the Heat Shock Factors (HSFs) and Heat Shock Proteins (HSPs), are also important regulatory targets in the progression of neurodegenerative diseases and cancers. Modulation of the HSR and/or its extended network have, therefore, become attractive treatment strategies for these diseases. Development of effective therapies will, however, require a detailed understanding of the HSR, important features of which continue to be uncovered and are yet to be completely understood. We review recently described and hallmark mechanistic principles of the HSR, the regulation and functions of HSPs, and contexts in which the HSR is activated and influences cell fate in response to various toxic conditions.

TRP Channel Involvement in Salivary Glands-Some Good, Some Bad

Salivary glands secrete saliva, a mixture of proteins and fluids, which plays an extremely important role in the maintenance of oral health. Loss of salivary secretion causes a dry mouth condition, xerostomia, which has numerous deleterious consequences including opportunistic infections within the oral cavity, difficulties in eating and swallowing food, and problems with speech. Secretion of fluid by salivary glands is stimulated by activation of specific receptors on acinar cell plasma membrane and is mediated by an increase in cytosolic [Ca²⁺] ([Ca²⁺]_i). The increase in [Ca²⁺]_i regulates a number of ion channels and transporters that are required for establishing an osmotic gradient that drives water flow via aquaporin water channels in the apical membrane. The Store-Operated Ca²⁺ Entry (SOCE) mechanism, which is regulated in response to depletion of ER-Ca²⁺, determines the sustained [Ca²⁺]_i increase required for prolonged fluid secretion. Core components of SOCE in salivary gland acinar cells are Orai1 and STIM1. In addition, TRPC1 is a major and non-redundant contributor to SOCE and fluid secretion in salivary gland acinar and ductal cells. Other TRP channels that contribute to salivary flow are TRPC3 and TRPV4, while presence of others, including TRPM8, TRPA1, TRPV1, and TRPV3, have been identified in the gland. Loss of salivary gland function leads to dry mouth conditions, or xerostomia, which is clinically seen in patients who have undergone radiation treatment for head-and-neck cancers, and those with the autoimmune exocrinopathy, Sjögren’s syndrome (pSS). TRPM2 is a unique TRP channel that acts as a sensor for intracellular ROS. We will discuss recent studies reported by us that demonstrate a key role for TRPM2 in radiation-induced salivary gland dysfunction. Further, there is increasing evidence that TRPM2 might be involved in inflammatory processes. These interesting findings point to the possible involvement of TRPM2 in Sjögren’s Syndrome, although further studies will be required to identify the exact role of TRPM2 in this disease.

Anti-TNFα therapy in inflammatory lung diseases

Increased levels of tumor necrosis factor (TNF) α have been linked to a number of pulmonary inflammatory diseases including asthma, chronic obstructive pulmonary disease (COPD), acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), sarcoidosis, and interstitial pulmonary fibrosis (IPF). TNFα plays multiple roles in disease pathology by inducing an accumulation of inflammatory cells, stimulating the generation of inflammatory mediators, and causing oxidative and nitrosative stress, airway hyperresponsiveness and tissue remodeling. TNFα-targeting biologics, therefore, present a potentially highly efficacious treatment option. This review summarizes current knowledge on the role of TNFα in pulmonary disease pathologies, with a focus on the therapeutic potential of TNFα-targeting agents in treating inflammatory lung diseases.

Targeting Antioxidant Pathways with Ferrocenylated N-Heterocyclic Carbene Supported Gold(I) Complexes in A549 Lung Cancer Cells

Ferrocenylated-Au(i) carbenes were designed, synthesized, and studied for their ability to generate reactive oxygen species and target antioxidant pathways via multiple mechanisms.

Ferrocene containing N-heterocyclic carbene (NHC) ligated gold(i) complexes of the type [Au(NHC)₂]⁺ were prepared and found to be capable of regulating the formation of reactive oxygen species (ROS) via multiple mechanisms. Single crystal X-ray analysis of bis(1-(ferrocenylmethyl)-3-mesitylimidazol-2-ylidene)-gold(i) chloride (5) and bis(1,3-di(ferrocenylmethyl)imidazol-2-ylidene)-gold(i) chloride (6) revealed a quasi-linear geometry around the gold(i) centers (i.e., the C–Au–C bond angle were measured to be ∼177° and all the Au–C_carbene bonds distances were in the range of 2.00 (7)–2.03 (1) Å). A series of cell studies indicated that cell proliferation inhibition and ROS generation were directly proportional to the amount of ferrocene contained within the [Au(NHC)₂]⁺ complexes (IC₅₀ of 6 < 5 < bis(1-benzyl-3-mesitylimidazol-2-ylidene)-gold(i) chloride (4)). Complexes 4–6 were also confirmed to inhibit thioredoxin reductase as inferred from lipoate reduction assays and increased chelatable intracellular zinc concentrations. RNA microarray gene expression assays revealed that 6 induces endoplasmic reticulum stress response pathways as a result of ROS increase.

Oxidative stress in Fanconi anaemia: from cells and molecules towards prospects in clinical management

Fanconi anaemia (FA) is a genetic disease featuring bone marrow failure, proneness to malignancies, and chromosomal instability. A line of studies has related FA to oxidative stress (OS). This review attempts to evaluate the evidence for FA-associated redox abnormalities in the literature from 1981 to 2010. Among 2170 journal articles on FA evaluated, 162 related FA with OS. Early studies reported excess oxygen toxicity in FA cells that accumulated oxidative DNA damage. Prooxidant states were found in white blood cells and body fluids from FA patients as excess luminol-dependent chemiluminescence, 8-hydroxy-deoxyguanosine, reduced glutathione/oxidized glutathione imbalance, and tumour necrosis factor-α. Some FA gene products involved in redox homeostasis can be summarized as follows: (a) FANCA, FANCC, and FANCG interact with cytochrome P450-related activities and/or respond to oxidative damage; (b) FANCD2 in OS response interacts with forkhead box O3 and ataxia telangiectasia mutated protein; (c) FANCG is found in mitochondria and interacts with PRDX3, and FA-G cells display distorted mitochondria and decreased peroxidase activity; (d) FANCJ (BACH1/BRIP1) is a repressor of haeme oxygenase-1 gene and senses oxidative base damage; (e) antioxidants, such as tempol and resveratrol decrease cancer incidence and haematopoietic defects in Fancd2(-/-) mice. The overall evidence for FA-associated OS may suggest designing chemoprevention studies aimed at delaying the onset of OS-related clinical complications.

Sjøgren's syndrome-associated oxidative stress and mitochondrial dysfunction: prospects for chemoprevention trials

An involvement of oxidative stress (OS) was found in recent studies of Sjøgren's syndrome (SS) that reported significant changes in protein oxidation, myeloperoxidase activity, TNF-α, nitrotyrosine, and GSH levels in plasma from SS patients. Excess levels of OS markers, as oxidative DNA damage and propanoyl-lysine, were reported in saliva from SS patients. Previous reports concurred with a role of OS in SS pathogenesis, by showing a decreased expression of antioxidant activities in conjunctival epithelial cells of SS patients and in parotid gland tissue samples from SS patients. A link between OS and mitochondrial dysfunction (MDF) is recognized both on the grounds of the established role of mitochondria in reactive oxygen species (ROS) formation and by the occurrence of MDF in a set of OS-related disorders. Earlier studies detected mitochondrial alterations in cells from SS patients, related to the action of antimitochondrial autoantibodies, and affecting specific mitochondrial activities. Thus, a link between MDF and OS may be postulated in SS, prompting studies aimed at elucidating SS pathogenesis and in the prospect of chemoprevention trials in SS clinical management.

Ochratoxin A causes oxidative stress and cell death in rat liver

The effect of ochratoxin A (OTA) on oxidant/antioxidant status and on histopathological changes and apoptotic cell death in livers of male Sprague-Dawley rats has been investigated. OTA (0.5 mg/kg body weight/day) was administered by oral route for 14 days. Plasma biochemical parameters, activities of liver selenoenzymes (glutathione peroxidase-1, thioredoxin reductase) and antioxidant enzymes (catalase, superoxide dismutase, glutathione S-transferase), and levels of total glutathione and thiobarbituric acid reactive substance in hepatic tissue were measured. In addition, histopathological examinations were performed and apoptotic cell death of hepatocytes was evaluated by the TdT-mediated dUTP nick-end labelling (TUNEL) assay. OTA exposure was found to induce focal necrosis of hepatocytes and mononuclear cell infiltration. Besides, exposure to OTA caused an imbalance in oxidant and antioxidant parameters in the rat liver, as evidenced by significant decreases in glutathione S-transferase activity and glutathione levels, and marked increases in concentrations of thiobarbituric acid reactive substances. Furthermore, TUNEL analysis revealed a significant ~2.7-fold increase in the number of TUNEL-positive liver cells of rats exposed to OTA compared to the control group. The results of this study showed that oxidative stress is at least one of the mechanisms underlying the hepatic toxicity of OTA, and that both necrosis and apoptosis are types of cell death in the hepatic toxicity of this mycotoxin.

Taxol-oligoarginine conjugates overcome drug resistance in-vitro in human ovarian carcinoma

OBJECTIVE

Multidrug resistance is the major cause of failure of many chemotherapeutic agents. While resistance can arise from several factors, it is often dominated by drug efflux mediated by P-glycoprotein (P-gp), a membrane-bound polysubstrate export pump expressed at high levels in resistant cells. While co-administration of pump inhibitors and a drug could suppress efflux, this two-drug strategy has not yet advanced to therapy. We recently demonstrated that the reversible attachment of a guanidinium-rich molecular transporter, polyarginine, to a drug provides a conjugate that overcomes efflux-based resistance in cells and animals. This study is to determine whether this strategy for overcoming resistance is effective against human disease.

METHODS

Tumor samples from ovarian cancer patients, both malignant ascites cells and dissociated solid tumor cells, were exposed to Taxol-oligoarginine conjugates designed to release free drug only after cell entry. Cell viability was determined via propidium-iodide uptake by flow cytometry. To analyze bystander effect, toxicity of the drug conjugates was also tested on peripheral blood leucocytes.

RESULTS

Human ovarian carcinoma specimens resistant to Taxol in vitro demonstrated increased sensitivity to killing by all Taxol-transporter conjugates tested. These studies also show that the drug conjugates were not significantly more toxic to normal human peripheral blood leukocytes than Taxol.

CONCLUSIONS

These studies with human tumor indicate that oligoarginine conjugates of known drugs can be used to overcome the efflux-based resistance to the drug, providing a strategy that could improve the treatment outcomes of patients with efflux-based drug-resistance.

Aldose reductase inhibition suppresses oxidative stress-induced inflammatory disorders

Oxidative stress-induced inflammation is a major contributor to several disease conditions including sepsis, carcinogenesis and metastasis, diabetic complications, allergic asthma, uveitis and after cataract surgery posterior capsular opacification. Since reactive oxygen species (ROS)-mediated activation of redox-sensitive transcription factors and subsequent expression of inflammatory cytokines, chemokines and growth factors are characteristics of inflammatory disorders, we envisioned that by blocking the molecular signals of ROS that activate redox-sensitive transcription factors, various inflammatory diseases could be ameliorated. We have indeed demonstrated that ROS-induced lipid peroxidation-derived lipid aldehydes such as 4-hydroxy-trans-2-nonenal (HNE) and their glutathione-conjugates (e.g. GS-HNE) are efficiently reduced by aldose reductase to corresponding alcohols which mediate the inflammatory signals. Our results showed that inhibition of aldose reductase (AKR1B1) significantly prevented the inflammatory signals induced by cytokines, growth factors, endotoxins, high glucose, allergens and auto-immune reactions in cellular as well as animal models. We have demonstrated that AKR1B1 inhibitor, fidarestat, significantly prevents tumor necrosis factor-alpha (TNF-α)-, growth factors-, lipopolysachharide (LPS)-, and environmental allergens-induced inflammatory signals that cause various inflammatory diseases. In animal models of inflammatory diseases such as diabetes, cardiovascular, uveitis, asthma, and cancer (colon, breast, prostate and lung) and metastasis, inhibition of AKR1B1 significantly ameliorated the disease. Our results from various cellular and animal models representing a number of inflammatory conditions suggest that ROS-induced inflammatory response could be reduced by inhibition of AKR1B1, thereby decreasing the progression of the disease and if the therapy is initiated early, the disease could be eliminated. Since fidarestat has already undergone phase III clinical trial for diabetic neuropathy and found to be safe, though clinically not very effective, our results indicate that it can be developed for the therapy of a number of inflammation-related diseases. Our results thus offer a novel therapeutic approach to treat a wide array of inflammatory diseases.

Comparative studies of the effects of Tabebuia avellanedae bark extract and beta-lapachone on the hematopoietic response of tumour-bearing mice

The effects of Tabebuia avellanedae (TACE), traditionally prescribed in the treatment of cancer, and the naphtoquinone beta-lapachone (beta-lap) on the growth and differentiation of granulocyte and macrophage progenitor cells (CFU-GM) were studied in Ehrlich ascites tumour-bearing mice. Myelosuppression concomitant with increases in spleen CFU-GM and in serum colony-stimulating activity (CSA) were observed in these animals. Treatment with TACE (30-500 mg/kg) and beta-lap (1-5mg/kg) reversed these effects in a dose-dependent manner. The optimal biologically active doses of 120 mg/kg TACE and 1mg/kg beta-lap prolonged life span of tumour-bearing mice, both producing the same rate of extension in the duration of survival. Toxic manifestations were produced by the higher doses of beta-lap in normal and tumour-bearing mice. In spite of similarities between treatments, TACE concentrations used to treat the animals presented no traces of beta-lap, as measured by TLC and HPLC analyses. Our findings suggest that the antitumour effect of TACE and beta-lap, acting synergistically with other factors, such as specific cytokines, may result from enhanced macrophage activation against tumour cells. In addition, it is clear from our results that hematopoietic disorders produced by tumours are an important pathological condition that must be considered in drug development.

Malignant ascites increases the antioxidant ability of human ovarian (SKOV-3) and gastric adenocarcinoma (KATO-III) cells

OBJECTIVES

The antioxidant status of cancer cells is an important factor in tumor invasion and metastases. This study investigated whether metastatic cancer cells derive beneficial antioxidant protection from ascitic fluid and are rendered resistant to oxidative stress in the form of a chemically generated free radical insult.

METHODS

Human gastric carcinoma (KATO-III) and ovarian adenocarcinoma (SKOV-3) cell lines were cultured and incubated for 24 h with (1) M199 medium; (2) M199 + 20% fetal calf serum (FCS); (3) malignant ascites. All cells were exposed to a hydroxyl radical-generating system for 1 h. Cellular lipid peroxidation was assessed by measuring malondialdehyde (MDA) in cell suspensions. Glutathione (GSH) levels in cell pellet were measured in SKOV-3 cells after 0, 24, 48, and 72 h of incubation with buthionine sulphoximine (BSO). CD44 gene expression of cancer cells was analyzed by Northern blotting.

RESULTS

The results showed that the cancer cells were rendered resistant to oxidative stress and with upregulated CD44 gene expression by components of malignant ascites.

CONCLUSIONS

These findings suggest that malignant ascites increases the antioxidant ability of cancer cells and the potential of adhesion and invasion. Thus, determination of the nature of these putative tumor-protective components of ascites may provide targets for therapeutic intervention.

Lysosomal enzymes promote mitochondrial oxidant production, cytochrome c release and apoptosis

Exposure of mammalian cells to oxidant stress causes early (iron catalysed) lysosomal rupture followed by apoptosis or necrosis. Enhanced intracellular production of reactive oxygen species (ROS), presumably of mitochondrial origin, is also observed when cells are exposed to nonoxidant pro-apoptotic agonists of cell death. We hypothesized that ROS generation in this latter case might promote the apoptotic cascade and could arise from effects of released lysosomal materials on mitochondria. Indeed, in intact cells (J774 macrophages, HeLa cells and AG1518 fibroblasts) the lysosomotropic detergent O-methyl-serine dodecylamide hydrochloride (MSDH) causes lysosomal rupture, enhanced intracellular ROS production, and apoptosis. Furthermore, in mixtures of rat liver lysosomes and mitochondria, selective rupture of lysosomes by MSDH promotes mitochondrial ROS production and cytochrome c release, whereas MSDH has no direct effect on ROS generation by purifed mitochondria. Intracellular lysosomal rupture is associated with the release of (among other constituents) cathepsins and activation of phospholipase A2 (PLA2). We find that addition of purified cathepsins B or D, or of PLA2, causes substantial increases in ROS generation by purified mitochondria. Furthermore, PLA2 - but not cathepsins B or D - causes rupture of semipurified lysosomes, suggesting an amplification mechanism. Thus, initiation of the apoptotic cascade by nonoxidant agonists may involve early release of lysosomal constituents (such as cathepsins B and D) and activation of PLA2, leading to enhanced mitochondrial oxidant production, further lysosomal rupture and, finally, mitochondrial cytochrome c release. Nonoxidant agonists of apoptosis may, thus, act through oxidant mechanisms.

Human TNF-alpha in transgenic mice induces differential changes in redox status and glutathione-regulating enzymes

Tumor necrosis factor a (TNF-alpha) is a pleiotropic cytokine involved in several diseases. Various effects of TNF-alpha are mediated by the induction of a cellular state consistent with oxidative stress. Glutathione (GSH) is a major redox-buffer of eukaryotic cells and is important in the defense against oxidative stress. We hypothesized that persistent TNF-alpha secretion could induce oxidative stress through modulation of GSH metabolism. This hypothesis was examined in a transgenic mouse model with low, persistent expression of human TNF-alpha in the T cell compartment. Major findings were i) marked tissue-specific changes in GSH redox status and GSH regulating enzymes, with the most pronounced changes in liver; ii) moderate changes in GSH metabolism and up-regulation of GSH-regulating enzymes were observed in lung and kidney from transgenic mice; and iii) liver, lung and kidney from transgenic mice had decreased levels of total glutathione, whereas splenic CD4+ and CD8+ T cells had a marked increase in oxidized glutathione as the major change. Oxidative stress induced by persistent low-grade exposure to TNF-alpha in transgenic mice appears to involve marked organ-specific alterations in glutathione redox status and glutathione-regulating enzymes with the most pronounced changes in the liver. These mice constitute a useful model for immunodeficiency syndromes and chronic inflammatory diseases involving pathogenic interaction between TNF-alpha and oxidative stress.

The effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on oxidative enzymes in adipocytes and liver

Reactive oxygen species are produced in response to environmental toxins, and previous studies have suggested that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) damages a number of target organs through the generation of oxygen free radicals and oxidative stress. Upon exposure, TCDD becomes concentrated in adipose tissue, and adversely affects many organs, including liver. This study examined whether oxidative stress was induced in adipocytes and liver that were exposed to TCDD. 3T3-F442A adipocyte cultures were treated with TCDD (5-200 nM) for up to 72 h, and the activity and mRNA levels of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) in adipocyte cell lysates were measured. The addition of 50 nM TCDD induced a two-fold increase in SOD activity after 48 h (P<0.05). In contrast, TCDD had no significant effect on the activity of catalase or GSH-Px in the adipocytes, and the increase in SOD activity was not accompanied by a change in SOD mRNA levels. To assess the effects of TCDD on oxidative stress enzymes in vivo, male Sprague-Dawley rats were injected weekly for 8 weeks with 30 ng/kg TCDD. In addition, the rats were fed either a low-fat complex-carbohydrate (LFCC) diet, or a high fat sucrose diet (HFS). The HFS diet has previously been shown to induce mild obesity and insulin resistance, without inducing diabetes. SOD, catalase, and GSH-Px activities were measured in the liver and adipose tissue of these rats. TCDD injection resulted in a 52% decrease in catalase activity in the adipose tissue of HFS rats (P<0.05). In contrast, SOD and GSH-Px activities were not altered in adipose tissue of TCDD-injected rats. In liver, however, there were significant decreases in GSH-Px activity in response to TCDD. This effect of TCDD was observed in both the LFCC and HFS dietary groups. In addition, GSH-Px activity in the HFS rats was significantly decreased when compared to GSH-Px activity in LFCC rats, in both TCDD-treated and control groups, suggesting that TCDD and a high fat diet may combine to exacerbate oxidative stress. Thus, TCDD induces complex changes in enzymes of oxidative stress in both adipocytes and liver. In adipocytes, these changes occurred post-transcriptionally, as there were no changes in mRNA levels. In addition, a high fat diet per se also resulted in a decrease in GSH-Px activity in liver.

Characterization of graft-versus-host disease in SCID mice and prevention by physicochemical stressors

BACKGROUND

Graft versus host disease (GVHD) prevents potentially curative allogeneic stem cell transplantation from being offered to cancer patients who lack a suitably matched donor. New methods to prevent GVHD are required to allow successful transplants across major histocompatibility complex barriers.

METHODS

A model of GVHD in C.B-17 SCID mice was developed to allow the study of allo-activated donor T cells without confounding effects of host lymphocytes. The abilities of cyclosporin-A, anticytokine antibodies, and oxidative stress to prevent GVHD in this model was studied.

RESULTS

T cells from major histocompatibility-mismatched donor mice caused severe GVHD in sublethally irradiated SCID hosts that could be ameliorated by coadministration of donor bone marrow but not by cyclosporine-A or anticytokine antibodies. In contrast, three-log more T cells could be injected without clinical consequences if they had been pretreated with a combination of heat, ultraviolet light, and oxygenation. The effect was not the trivial result of donor T cell destruction because T cell reconstitution, although delayed, recovered to normal levels within 2 weeks. Protection from GVHD required oxygenation and was associated with normalization of the CD4/CD8 donor T cell ratio, recovery of host hematopoiesis, and decreased inflammatory cytokine production.

CONCLUSION

Pretreatment of donor T cells with a combination of physicochemical stressors effectively prevents GVHD caused by major major histocompatibility disparities and may facilitate the safe transplantation of patients without HLA-identical donors.

Imiquimod therapy for molluscum contagiosum

BACKGROUND

Molluscum contagiosum virus (MCV) is a large double-stranded DNA virus that is a member of the family Poxviridae, and which has a worldwide distribution. As with other poxviruses, MCV does not appear to develop latency but evades the immune system through the production of viral specific proteins.

OBJECTIVE

To evaluate the therapeutic efficacy of imiquimod 5% cream for MCV.

METHODS

Thirteen children >5 and <10 years old, 19 immune-competent adults and four adults with advanced, but stable HIV-1 disease with >10 MCV lesions were treated with topical 5% imiquimod cream three times weekly for up to 16 weeks.

RESULTS

Fourteen of 19 immune-competent adults, four of four adults with HIV-1 disease, and six of 13 children had resolution of their MCV lesions in <16 weeks of imiquimod therapy. Children tended to have more pruritus and inflammatory reactions with imiquimod, although most treated lesions appeared to respond. The development of new MCV lesions resulted in a lower overall resolution of the lesions in children. Imiquimod appeared to be the most efficacious in patients with HIV-1 disease and in the genital area in immune-competent adults.

CONCLUSION

Although topical imiquimod appears to have some efficacy in the therapy of MCV, in children the pruritus correlated relatively well with the development of new lesions. In adults, areas that would be expected to have better penetration appeared to respond more consistently. Although the HIV-1-positive patients had the largest clinical lesions at the onset of therapy, as a group they had the best overall response to therapy.

Myelopoietic response in tumour-bearing mice by an aggregated polymer isolated from Aspergillus oryzae

The effects of magnesium ammonium phospholinoleate-palmitoleate anhydride (MAPA), a proteic aggregated polymer isolated from Aspergillus oryzae, on the growth and differentiation of granulocyte-macrophage progenitor cells (colony-forming unit-granulocyte-macrophage [CFU-GM]) in normal and Ehrlich ascites tumour-bearing mice were studied. Myelosuppression concomitant with increased numbers of spleen CFU-GM was observed in tumour-bearing mice. Treatment of these animals with MAPA (0.5-10 mg/kg) stimulated marrow myelopoiesis in a dose-dependent manner and reduced spleen colony formation. No changes were observed in total and differential marrow cell counts. The dose of 5.0 mg/kg MAPA, given prior or after tumour inoculation, was the optimal biologically active dose in tumour-bearing mice and this dose schedule also stimulated myelopoiesis in normal mice. MAPA significantly enhanced survival and concurrently reduced tumour growth in the peritoneal cavity. We propose that the modulatory effect of MAPA on the myelopoietic response may be related to its antitumour activity as a possible mechanism for regulation of granulocyte-macrophage production and expression of functional activities.