Levamisole induced apoptosis in cultured vascular endothelial cells

Chronic levamisole exposure in male rats alters sexual behavior and induces apoptosis in the testis

Levamisole is an anti-helminthic drug developed and introduced in veterinary medicine, and it has been used more frequently after the inclusion of its usage in human medicine regarding disorders with immunomodulatory properties. In recent years, it has started to attract attention since it has beneficial effects on the treatment of COVID-19 due to its immunomodulatory properties. To investigate the effects of levamisole on sexual behavior and the reproductive system in male rats, two groups were formed the vehicle (n = 10) and levamisole (n = 10) groups. The vehicle group was given purified water whereas the levamisole group was administered with levamisole (2 mg/kg) by oral gavage daily for 4 weeks. Levamisole treatment significantly increased the mount latency (ML, P < 0.001) as well as the intromission latency (IL, P < 0.01). It also significantly prolonged postejaculatory interval (PEI, P < 0.01), decreased copulatory rate (CR, P < 0.05), and sexual activity index (SAI, P < 0.05). It significantly decreased serum monoamine oxidase A (MAO-A) levels (P < 0.05). Additionally, levamisole induced disorganizations of germinal epithelial cells of seminiferous tubules, congestion, edema in the interstitial area, and metaphase arrest in some spermatocytes (P < 0.001), and it significantly increased the immunohistochemical expressions of apoptotic Bax and cytochrome c, which is crucial proapoptotic protein, in the testis (P < 0.001). Also, levamisole significantly upregulated the mRNA levels of the apoptosis-related key regulatory genes, including Bax (Bcl-2-associated X protein, P = 0.05) and Bax/Bcl-2 ratio (P < 0.01) in testis. The current research is the first to show that levamisole may decrease sexual performance, potency, sexual motivation, and libido and induce apoptosis in the testis.

Levamisole Impairs Vascular Function by Blocking α-Adrenergic Receptors and Reducing NO Bioavailability in Rabbit Renal Artery

Levamisole is an anthelmintic drug restricted to veterinary use but is currently detected as the most widely used cocaine cutting agent in European countries. Levamisole-adulterated cocaine has been linked to acute kidney injury, marked by a decrease in glomerular filtration rate, which involves reduced renal blood flow, but data on the alteration of renovascular response produced by levamisole are scarce. Renal arteries were isolated from healthy rabbits and used for isometric tension recording in organ baths and protein analysis. We provide evidence that depending on its concentration, levamisole modulates renovascular tone by acting as a non-selective α-adrenergic receptor blocker and down-regulates α1-adrenoceptor expression. Furthermore, levamisole impairs the endothelium-dependent relaxation induced by acetylcholine without modifying endothelial nitric oxide synthase (eNOS) expression. However, exposure to superoxide dismutase (SOD) partially prevents the impairment of ACh-induced relaxation by levamisole. This response is consistent with a down-regulation of SOD1 and an up-regulation of NADPH oxidase 4 (Nox4), suggesting that endothelial NO loss is due to increased local oxidative stress. Our findings demonstrate that levamisole can interfere with renal blood flow and the coordinated response to a vasodilator stimulus, which could worsen the deleterious consequences of cocaine use.

Effect of a Single and Triple Dose of Levamisole on Hematological Parameters in Controlled Inflammation Model

This study aimed to evaluate the impact of single and triple administration of levamisole on the dynamics of hematological parameters during experimental pleuritis. The experiment was performed on female Buffalo rats. Rats were randomly assigned to two equal groups that received 1 and 3 doses of levamisole every 2, 24 and 48 h, respectively. Following the experiment, blood samples for the measurement of hematological parameters were collected. The study group receiving three doses of levamisole observed a significant reduction of red blood cell count at 48 h post administration and an increase in mean corpuscular volume compared to the control inflammation group. The administration of a single dose of levamisole results in a significant increase in hematocrit at 72 h, an increase in white blood cell count at 24 h and 72 h, and an increase in neutrophil count at 72 h compared to the control inflammation group. Administration of a single and triple dose of levamisole showed statistically significant modification of some hematological parameters and thus modulates the inflammatory process. In the lungs, this results in a reduction in leukocyte infiltrations around the bronchi and blood vessels.

Levamisole, a cocaine cutting agent, induces acute and subchronic systemic alterations in Wistar rats

The use of the anthelmintic levamisole as a cocaine adulterant has been increasing worldwide. Complications caused by this association include systemic vasculitis, agranulocytosis, neutropenia, tissue necrosis, pulmonary hemorrhage, and renal injury. Data about toxicity of levamisole are scarce, therefore the aim of this study was to evaluate the acute and subchronic toxic effects of levamisole in rats. Male Wistar rats received saline or levamisole by intraperitoneal route at the doses of 12, 24 and 36 mg/kg in the acute toxicity test; and at 3, 6 and 12 mg/kg in the subchronic toxicity test. Toxicity was evaluated using behavioral, cognitive, renal, hematological, biochemical and histopathological parameters. Acute administration of levamisole caused behavioral and histopathological alterations. Subchronic administration caused behavioral, cognitive and hematological alterations (p < 0.0001 and p < 0.05, respectively), impairment of liver and kidney functions (p < 0.05), and changes of antioxidant defenses (p ≤ 0.0001). Both administrations produced toxic effects of clinical relevance, which make levamisole a dangerous cutting agent. Furthermore, the knowledge of these effects can contribute to the correct diagnosis and treatment of cocaine dependents with unusual systemic alterations.

Effect of levamisole on expression of CD138 and interleukin-6 in human multiple myeloma cell lines

INTRODUCTION

Multiple myeloma (MM) is a B-cell malignancy accounting for 0.8% of all cancer deaths globally. This malignancy is characterized by lytic bone disease renal insufficiency, anemia, hypercalcemia, and immunodeficiency. The myeloma cells have enhanced expression of CD138. CD138 is a transmembrane heparin sulfate glycoprotein expressed on different types of adherent and nonadherent cells.CD138 is used as a standard marker for identification of tumor cells.

AIMS AND OBJECTIVES

Despite introduction of many therapeutic agents, the management of multiple myeloma (MM) remains a challenge and search for new therapeutic agents is in progress. In this study, we attempted to evaluate the effect of an alkaline phosphatase inhibitor, levamisole on expression of CD138, and level of interleukin-6 (IL-6) in human MM cell lines RPMI 8226 and U266 B1.

MATERIAL AND METHODS

U266B1 and RPMI 8226 cell lines were obtained from the National Centre for Cell Sciences, Pune. Alkaline phosphatase assay, Interleukin-6 assay and CD138 expression on myeloma cells by flow cytometry were investigated when the cells were exposed to Levamisole.

RESULTS

Levamisole-mediated growth inhibition of myeloma cells in vitro is associated with a loss of CD138 and increased IL-6 secretion. The increased secretion of IL-6 by myeloma cells could be an attempt to protect themselves from apoptosis.

CONCLUSION

Levamisole inhibited CD138 expression and affected the levels of IL-6 in a dose-dependent manner. The results of the present study add new dimension to levamisole's mode of action as inhibitor of CD138 and IL-6 and as an antiapoptotic agent.

Synthesis of imidazo-thiadiazole linked indolinone conjugates and evaluated their microtubule network disrupting and apoptosis inducing ability

A series of imidazo[2,1-b][1,3,4]thiadiazole linked indolinone conjugates were synthesized and investigated for antiproliferative activity in different human cancer cell lines by changing various substitutions at indolinone and phenyl ring systems. Among them conjugates 7, 14 and 15 were exhibited potent antiproliferative activity with GI₅₀ values from 0.13 to 3.8 μΜ and evaluated for cell cycle analysis, tubulin polymerization assay and apoptosis. Treatment with 7, 14 and 15 were resulted in accumulation of cells in G2/M phase, inhibition of tubulin assembly, disruption of microtubule network. Inhibition of tubulin polymerization was further supported by Western blot analysis. In addition, the conjugates (7, 14 and 15) also showed apoptosis in HeLa cell line, detailed biological studies such as Hoechst 33,258 staining, DNA fragmentation and caspase-3 assays suggested that these compounds induce cell death by apoptosis. Docking studies revealed that these compounds (7, 14 and 15) bind with αAsn101, αThr179, αSer178, βCys241, βLys254 and βLys352 in the colchicine-binding site of the tubulin.

Cocaine induced pleural and pericardial effusion syndrome

A 42-year-old African American female with chronic cocaine use for 20 years, presented with two-day history of exertional shortness of breath and pleuritic chest pain. She was admitted three years back with acute kidney injury and skin rashes. At that time, skin biopsy was consistent with leukocytoclastic vasculitis and renal biopsy revealed proliferative glomerulonephritis. She responded to oral prednisone and mycophenolate with complete recovery of her kidney functions. Skin rash was waxing and waning over the last two years. On the second admission, patient was found to have large pleural effusion on computerized tomography scan and pericardial effusion on echocardiogram as shown in the figures. Pleural fluid analysis was exudative. Her serology was negative for ANA (antineutrophilic antibody) and anti-dsDNA (double stranded DNA). Complements levels were normal. She had positive low titers of ANCA levels. The patient was started on a course of prednisone for 6 months. Her pleural and pericardial effusion resolved completely on follow-up imaging with computerized tomography scan and echocardiogram. This case is unique since the pericardial and pleural effusions developed without any other etiology in the setting of cocaine; hence, we describe this clinical syndrome as cocaine induced pleural and pericardial effusions syndrome (CIPP).

Tetramisole and Levamisole Suppress Neuronal Activity Independently from Their Inhibitory Action on Tissue Non-specific Alkaline Phosphatase in Mouse Cortex

Tissue non-specific alkaline phosphatase (TNAP) may be involved in the synthesis of GABA and adenosine, which are the main inhibitory neurotransmitters in cortex. We explored this putative TNAP function through electrophysiological recording (local field potential ) in slices of mouse somatosensory cortex maintained in vitro. We used tetramisole, a well documented TNAP inhibitor, to block TNAP activity. We expected that inhibiting TNAP with tetramisole would lead to an increase of neuronal response amplitude, owing to a diminished availability of GABA and/or adenosine. Instead, we found that tetramisole reduced neuronal response amplitude in a dose-dependent manner. Tetramisole also decreased axonal conduction velocity. Levamisole had identical effects. Several control experiments demonstrated that these actions of tetramisole were independent from this compound acting on TNAP. In particular, tetramisole effects were not stereo-specific and they were not mimicked by another inhibitor of TNAP, MLS-0038949. The decrease of axonal conduction velocity and preliminary intracellular data suggest that tetramisole blocks voltage-dependent sodium channels. Our results imply that levamisole or tetramisole should not be used with the sole purpose of inhibiting TNAP in living excitable cells as it will also block all processes that are activity-dependent. Our data and a review of the literature indicate that tetramisole may have at least four different targets in the nervous system. We discuss these results with respect to the neurological side effects that were observed when levamisole and tetramisole were used for medical purposes, and that may recur nowadays due to the recent use of levamisole and tetramisole as cocaine adulterants.

Influence of levamisole and other angiogenesis inhibitors on angiogenesis and endothelial cell morphology in vitro

Angiogenesis, the formation of new blood vessels from existing vessels is required for many physiological processes and for growth of solid tumors. Initiated by hypoxia, angiogenesis involves binding of angiogenic factors to endothelial cell (EC) receptors and activation of cellular signaling, differentiation, migration, proliferation, interconnection and canalization of ECs, remodeling of the extracellular matrix and stabilization of newly formed vessels. Experimentally, these processes can be studied by several in vitro and in vivo assays focusing on different steps in the process. In vitro, ECs form networks of capillary-like tubes when propagated for three days in coculture with fibroblasts. The tube formation is dependent on vascular endothelial growth factor (VEGF) and omission of VEGF from the culture medium results in the formation of clusters of undifferentiated ECs. Addition of angiogenesis inhibitors to the coculture system disrupts endothelial network formation and influences EC morphology in two distinct ways. Treatment with antibodies to VEGF, soluble VEGF receptor, the VEGF receptor tyrosine kinase inhibitor SU5614, protein tyrosine phosphatase inhibitor (PTPI) IV or levamisole results in the formation of EC clusters of variable size. This cluster morphology is a result of inhibited EC differentiation and levamisole can be inferred to influence and block VEGF signaling. Treatment with platelet factor 4, thrombospondin, rapamycin, suramin, TNP-470, salubrinal, PTPI I, PTPI II, clodronate, NSC87877 or non-steriodal anti-inflammatory drugs (NSAIDs) results in the formation of short cords of ECs, which suggests that these inhibitors have an influence on later steps in the angiogenic process, such as EC proliferation and migration. A humanized antibody to VEGF is one of a few angiogenesis inhibitors used clinically for treatment of cancer. Levamisole is approved for clinical treatment of cancer and is interesting with respect to anti-angiogenic activity in vivo since it inhibits ECs in vitro with a morphology resembling that obtained with antibodies to VEGF.

Effect of cyanobacteria on immune function of crucian carp (Carassius auratus) via chronic exposure in diet

Cyanobacterial blooms caused by water eutrophication have become a worldwide problem. Microcystins (MCs) released during cyanobacterial blooms exert toxicity on fish. Up to now, immunotoxicity of MCs on fish has been rarely reported. The present study investigated immune response of crucian carp (Carassius auratus) to cyanobacteria via chronic exposure in diet. Fish were fed with diets containing 20% (low dose group) and 40% (high dose group) of cyanobacteria lyophilized powder. After exposure of 30 d, a batch of assays was determined for assessing immunotoxicity of MCs. The head kidney and spleen indexes significantly increased in high dose group. Blood nitroblue tetrazolium activity in high dose group was nearly twice as much as that in control group with no cyanobacteria additive. Marked haemorrhage and hyperemia were observed in kidney and spleen in high dose group. The edematous mitochondria, deformation of the nucleus and compaction of chromatin occurred in lymphocytes of head kidney and spleen in both cyanobacteria groups. Lysozyme activity showed an obvious increase in low dose group but a sharp decrease in high dose group. Significant increase of macrophage bactericidal activity was detected in low dose group. The present findings indicate that via chronic diet exposure of different cyanobacteria levels, fish exhibit various immune responses. Fish immunity tends to proceed toward the direction of immunostimulative response at low MCs concentrations but toward the trend of immunosuppressive answer at high MCs concentrations.

Novel levamisole derivative induces extrinsic pathway of apoptosis in cancer cells and inhibits tumor progression in mice

Background

Levamisole, an imidazo(2,1-b)thiazole derivative, has been reported to be a potential antitumor agent. In the present study, we have investigated the mechanism of action of one of the recently identified analogues, 4a (2-benzyl-6-(4′-fluorophenyl)-5-thiocyanato-imidazo[2,1-b][1], [3], [4]thiadiazole).

Materials and Methods

ROS production and expression of various apoptotic proteins were measured following 4a treatment in leukemia cell lines. Tumor animal models were used to evaluate the effect of 4a in comparison with Levamisole on progression of breast adenocarcinoma and survival. Immunohistochemistry and western blotting studies were performed to understand the mechanism of 4a action both ex vivo and in vivo.

Results

We have determined the IC₅₀ value of 4a in many leukemic and breast cancer cell lines and found CEM cells most sensitive (IC₅₀ 5 µM). Results showed that 4a treatment leads to the accumulation of ROS. Western blot analysis showed upregulation of pro-apoptotic proteins t-BID and BAX, upon treatment with 4a. Besides, dose-dependent activation of p53 along with FAS, FAS-L, and cleavage of CASPASE-8 suggest that it induces death receptor mediated apoptotic pathway in CEM cells. More importantly, we observed a reduction in tumor growth and significant increase in survival upon oral administration of 4a (20 mg/kg, six doses) in mice. In comparison, 4a was found to be more potent than its parental analogue Levamisole based on both ex vivo and in vivo studies. Further, immunohistochemistry and western blotting studies indicate that 4a treatment led to abrogation of tumor cell proliferation and activation of apoptosis by the extrinsic pathway even in animal models.

Conclusion

Thus, our results suggest that 4a could be used as a potent chemotherapeutic agent.

Anti-proliferative effect of levamisole on human myeloma cell lines in vitro

Levamisole has been employed as an immunomodulatory agent in conjunction with 5-fluorouracil in the treatment of colon cancer relapse. At high doses, levamisole has been shown to have both anti-cancer and immunosuppressive activities. In vitro, levamisole has been shown to potentiate the anti-proliferative effect of 5-fluorouracil in several types of tumor cell lines; however, its mechanism of cytotoxic action and its molecular targets in cells remains to be elucidated. Here, the effect of levamisole on the proliferative response of the human multiple myeloma cell lines RPMI 8226 and U266B1 was studied in vitro. Treatment of both lines with varying concentrations of levamisole for 48 and 72 h in culture resulted in a significant inhibition of proliferation (unstimulated) in a dose-dependent manner, as assessed by an 3-[(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide dye assay. Furthermore, measurements of cell viability (using a trypan blue dye exclusion assay) clearly showed that the levamisole was cytotoxic. The preliminary evaluation of the mechanism of this cytotoxic effect revealed that this drug induced apoptosis in the myeloma cells, as evidenced by increases in the levels of DNA fragmentation, release of cytochrome c into the cytoplasm, and the activation of caspase-3 activity in the cells. The results of these studies strongly suggest that levamisole could be a potent anti-myeloma agent and might be considered in the treatment of multiple myeloma in the future.

Phosphatase inhibitors with anti-angiogenic effect in vitro

Levamisole has previously been identified as an inhibitor of angiogenesis in vitro and in vivo, but the mechanism behind the anti-angiogenic behavior has not yet been established. However, one known effect of levamisole is the inhibition of alkaline phosphatase, and this fact encouraged us to test other phosphatase inhibitors for their anti-angiogenic effects by using the same method as used to identify levamisole: an ELISA-based co-culture angiogenesis assay giving quantitative and qualitative results. Historically, intracellular phosphatases have been associated with the downregulation of signaling pathways, and kinases with their upregulation, but lately, the phospatases have also been coupled to positive signaling, which is why inhibition of phosphatases has become associated with anti-tumorigenic and anti-angiogenic effects. The results obtained in this work reveal several agents with anti-angiogenic potential and give a strong indication that phosphatase inhibition is linked to anti-angiogenic activity. An apparent disruption of endothelial tube formation was seen for seven of eight phosphatase inhibitors tested in the angiogenesis assay. By looking at the morphological results, it was seen that most of the inhibitors impaired proliferation and elongation of the endothelial cells, which still had a differentiated appearance. One inhibitor, PTP inhibitor IV, seemed to impair endothelial cell differentiation and induced the same morphology as when cells were treated with levamisole, although at a 200 times lower concentration than that of levamisole. Hence, our work points out compounds with a potential that may be of use in the search for new medical products for the treatment of malignant tumors, or other conditions where angiogenesis plays a central role.

R-(+)-alpha-lipoic acid inhibits endothelial cell apoptosis and proliferation: involvement of Akt and retinoblastoma protein/E2F-1

Lipoic acid was recently demonstrated to improve endothelial dysfunction or retinopathy not only in rats but also in diabetic patients. We tested the hypothesis that R-(+)-alpha-lipoic acid (LA) directly affects human endothelial cell (EC) function (e.g., apoptosis, proliferation, and protein expression), independent of the cells' vascular origin. Macrovascular EC (macEC), isolated from umbilical (HUVEC) and adult saphenous veins and from aortae, as well as microvascular EC (micEC) from retinae, skin, and uterus, were exposed to LA (1 mumol/l-1 mmol/l) with/without different stimuli (high glucose, TNF-alpha, VEGF, wortmannin, LY-294002). Apoptosis, proliferation, cell cycle distribution, and protein expression were determined by DNA fragmentation assays, [(3)H]thymidine incorporation, FACS, and Western blot analyses, respectively. In macro- and microvascular EC, LA (1 mmol/l) reduced (P < 0.05) basal (macEC, -36 +/- 4%; micEC, -46 +/- 6%) and stimulus-induced (TNF-alpha: macEC, -75 +/- 11%; micEC, -68 +/- 13%) apoptosis. In HUVEC, inhibition of apoptosis by LA (500 mumol/l) was paralleled by reduction of NF-kappaB. LA's antiapoptotic activity was reduced by PI 3-kinase inhibitors (wortmannin, LY-294002), being in line with LA-induced Akt phosphorylation (Ser(437), +159 +/- 43%; Thr(308), +98 +/- 25%; P < 0.01). LA (500 mumol/l) inhibited (P < 0.001) proliferation of macEC (-29 +/- 3%) and micEC (-29 +/- 3%) by arresting the cells at the G(1)/S transition due to an increased ratio of cyclin E/p27(Kip) (4.2-fold), upregulation of p21(WAF-1/Cip1) (+104 +/- 21%), and reduction of cyclin A (-32 +/- 11%), of hyperphosphorylated retinoblastoma protein (macEC: -51 +/- 7%; micEC: -50 +/- 15%), and of E2F-1 (macEC: -48 +/- 3%; micEC: -31 +/- 10%). LA's ability to inhibit apoptosis and proliferation of ECs could beneficially affect endothelial dysfunction, which precedes manifestation of late diabetic vascular complications.

Effect of liniment levamisole on cellular immune functions of patients with chronic hepatitis B

AIM

To explore the effects of liniment levamisole on cellular immune functions of patients with chronic hepatitis B.

METHODS

The levels of T lymphocyte subsets and mIL-2R in peripheral blood mononuclear cells (PBMCs) were measured by biotin-streptavidin (BSA) technique in patients with chronic hepatitis B before and after the treatment with liniment levamisole.

RESULTS

After one course of treatment with liniment levamisole, the levels of CD3(+), CD4(+), and the ratio of CD4(+)/CD8(+) increased as compared to those before the treatment but the level of CD8(+) decreased. The total expression level of mIL-2R in PBMCs increased before and after the treatment with liniment levamisole.

CONCLUSION

Liniment levamisole may reinforce cellular immune functions of patients with chronic hepatitis B.

The inhibition of angiogenesis by antisense oligonucleotides to clusterin

Angiogenesis is a primary disease target in ocular retinopathy and a secondary target in numerous other angiogenic diseases such as cancer, rheumatoid arthritis and psoriasis. Clinical trials using antiangiogenic antisense oligonucleotides (aso's) for the treatment of ocular disorders or cancer are well advanced. Clusterin aso's are currently under investigation for the treatment of prostate cancer. We have investigated the antiangiogenic properties of clusterin aso's using a capillary cell (HUVEC) viability assay. In this study we included aso's to known apoptosis modulators (bcl-2, bcl-xl and survivin) which were previously identified in HUVEC's. We have also studied the effect of clusterin aso's on angiogenesis using an in vitro, matrigel assay and on HUVEC apoptosis using an ELISA DNA fragmentation assay. Clusterin, bcl-2, bcl-xl and survivin aso's were all found to inhibit HUVEC growth. The apoptosis-inducing drugs paclitaxel, camptothecin and doxorubicin were also found to inhibit HUVEC proliferation. Combinations of aso's with these drugs demonstrated a minor additive but not synergistic inhibitory effect on HUVEC proliferation. Clusterin aso's were found to strongly inhibit angiogenesis and induce high levels of apoptosis in HUVECs. In cancer cells the prosurvival protein clusterin may protect the cells from apoptosis-inducing agents so that the clusterin aso's may act as chemosensitization agents. These data demonstrate a strong antiangiogenic action of clusterin aso's, that is not necessarily related to any chemosensitization effect of this agent.

[Immunity and immunosuppression in childhood idiopathic nephrotic syndrome]

Steroid sensitive idiopathic nephrotic syndrome is a T-cell disorder characterized by a functional renal impairment. Concluding a still relevant demonstration involving cellular immunity in the pathogenesis of the disease, R. Shalhoub in 1974 suggested a "special role for the thymus" based on the efficiency of steroids and alkylating agents, dramatic recoveries following measles, sensibility to bacterial infection due to a lack of cooperation between T and B cell and association to Hodgkin disease. As a matter of fact, the selected drugs based on medical empirism somehow enhance thymocytes apoptosis and negative selection of T cell, except cyclosporin. Steroids have been the first historical treatment of idiopathic nephrotic syndrome and have steadily been the first-line treatment for 50 years. Their unavoidable ability to induce rapid recovery of proteinuria and long-lasting or definite remission are dependent to a strict compliance to treatment. Indications of steroids-sparing treatments are not that clearcut in patients with steroids intoxication. Objectively, efficiency of levamisole and cyclophosphamide are much more limited than previously reported and cyclosporin nephrotoxicity might severely impair renal function following long-lasting treatment as well as it may paradoxically increase the activity of the disease. An alternate strategy to those currently adopted would use cyclosporin as the first-line steroids-sparing treatment during a very limited period, awaiting favourable ageing of patients and natural dampening activity of the disease to a full efficiency of alkylating agents. Compared to cyclophosphamide and cyclosporin, the relative safety of levamisole is encouraging to a more frequent uses. Its association to a full dose of prednisone in the treatment of the inaugural episode should be investigated. According to the limitations of those therapies, emerging drugs as mycophenolate might be worthwhile in the treatment of nephrotic patients.

Levamisole Inhibits Angiogenesis in vitro and Tumor Growth in vivo

The synthetic anthelmintic compound Levamisole has previously been used in cancer treatment as an adjuvant in combination with 5-fluorouracil. Its mode of action remains unclear, but an immune-stimulatory effect has been suggested. Here, we show that Levamisole inhibits angiogenesis in vitro and tumor growth in vivo. In vitro, Levamisole specifically inhibits proliferation and differentiation of endothelial cells propagated in co-culture with fibroblasts. In vivo, Levamisole inhibits the growth in nude mice of a transplanted human tumor. The use of nude mice as tumor hosts permits the discrimination between the angiogenesis inhibitory effect of Levamisole and its assumed immune-stimulatory effect. Our findings support a possible therapeutic effect of angiogenesis inhibitors in the treatment of cancer and call for further investigations of the mechanism(s) underlying the anti-angiogenic effect of Levamisole.

Induction of alkaline phosphatase in the inflamed intestine: a novel pharmacological target for inflammatory bowel disease

This study demonstrates the upregulation of alkaline phosphatase and the mechanisms involved in experimental colitis. All models of ileal and colonic inflammation examined, which were characterized by significant oxidative stress and neutrophil infiltration, resulted in an increase in alkaline phosphatase activity which was attributable to both epithelial cells and cells of the lamina propria, mainly leukocytes. The increase in alkaline phosphatase sensitivity to the inhibitors levamisole and homoarginine, together with changes in the apparent molecular size and in the sialization of the enzyme, indicated a change in the isoform expressed. An increase in tissue non-specific alkaline phosphatase expression was observed by Western blotting. Treatment with the bone/kidney alkaline phosphatase inhibitor levamisole or a monoclonal antibody resulted in significant protection from colonic inflammation. Taken together, these results indicate that the kidney isoform is a marker of intestinal inflammation and that it might even constitute a target for pharmacological intervention.

Adenylate kinase I does not affect cellular growth characteristics under normal and metabolic stress conditions

Adenylate kinase (AK)-catalyzed phosphotransfer is essential in the maintenance of cellular energetic economy in cells of fully differentiated tissues with highly variable energy demand, such as muscle and brain. To investigate if AK isoenzymes have a comparable function in the energy-demand management of proliferating cells, AK1 and AK1beta were expressed in mouse neuroblastoma N2a cells and in human colon carcinoma SW480 cells. Glucose deprivation, galactose feeding, and metabolic inhibitor tests revealed a differential energy dependency for these two cell lines. N2a cells showed a faster proliferation rate and strongest coupling to mitochondrial activity, SW480 proliferation was more dependent on glycolysis. Despite these differences, ectopic expression of AK1 or AK1beta did not affect their growth characteristics under normal conditions. Also, no differential effects were seen under metabolic stress upon treatment with mitochondrial and glycolytic inhibitors in in vitro culture or in solid tumors grown in vivo. Although many intimate connections have been revealed between cell death and metabolism, our results suggest that AK1- or AK1beta-mediated high-energy phosphoryl transfer is not a modulating factor in the survival of tumor cells during episodes of metabolic crisis.

Apoptosis by 6-O-palmitoyl-l-ascorbic acid coincides with JNK-phosphorylation and inhibition of Mg2+-dependent phosphatase activity

6-O-Palmitoyl ascorbic acid (PAA) has recently been used as a substitute for ascorbic acid because of its greater potency as an antioxidant. In detailed concentration response studies distinct cytotoxic effects of PAA at concentrations exceeding 100 microM were reported. Here we examined and further characterized this cytotoxicity. While ascorbic acid was tolerated well up to millimolar concentrations, PAA revealed an LC50 between 125 and 150 microM in rat GH3 tumor cells. Morphological and biochemical observations suggested the induction of apoptosis at concentrations exceeding 125 microM with a prominent activation of caspase 3 at 250 microM after 4 hr. A subsequent pronounced fragmentation of DNA (DNA-ladder) was detected after 6 hr and was further enhanced after 12 hr. The activation of caspases and the cleavage of its substrate PARP was preceded by a distinct increase in the phosphorylation of stress activated JNK-kinases. This observation suggested that the agent affected signal transduction mechanisms regulating protein phosphorylation at serine/threonine residues in the cell. No effect of PAA on protein phosphatase 2A (PP2A)-like activity was observed while magnesium-dependent protein phosphatase activity, presumably PP2C, was inhibited concentration-dependently up to 75% at the respective concentrations. Thus, the cytotoxic, pro-apoptotic effect of PAA might be related to the inhibition of PP2C and the activation of JNK.

Free fatty acids trigger apoptosis and inhibit cell cycle progression in human vascular endothelial cells

Plasma free fatty acid (FFA) concentrations are increased in states of insulin resistance and impair endothelial function. Because the underlying mechanisms are largely unknown, we examined selected, purified FFAs' (100-300 micromol/l, 24-48 h) action on apoptosis, cell cycle distribution, and associated gene/protein expression in human umbilical vein endothelial cells (HUVECs). Stearic acid, but not oleic acid, time and concentration dependently increased endothelial apoptosis by fivefold (n=6, P<0.01), whereas polyunsaturated FFAs (PUFAs; linoleic, gamma-linolenic, and arachidonic acid) exerted proapoptotic activity only at 300 micromol/l (P<0.05). Proapoptotic FFA action increased with FFAs' number of double bonds and with protein expression of the apoptosis promotor bak. The G0/G1 cell cycle arrest (n=6, P<0.05) induced by stearic acid (+14%) and PUFAs (+30%) is reflected by up-regulation of p21(WAF-1/Cip1). In addition, all FFAs concentration dependently reduced (P<0.05) gene/protein expression of clusterin (-54%), NF-kappaB's inhibitor, IkappaBalpha (-50%), endothelin-1 (-44%), and endothelial NO synthase (-44%). Plasma samples obtained from individuals with elevated plasma FFAs (372+/-22 micromol/l) increased endothelial apoptosis by 4.2-fold (P<0.001, n=10) compared with intra-individually matched low plasma FFA (56+/-21 micromol/l) conditions, underlining the results obtained by defined FFA stimulation. In conclusion, FFA structure differently affects endothelial cell proliferation and apoptosis, both representing key factors in the development of micro- and macrovascular dysfunction.

Diabetic LDL triggers apoptosis in vascular endothelial cells

This study compares the effects of LDL glycated either in vitro (LDL(iv)) or in vivo in diabetic patients (LDL(D)) on apoptosis, proliferation, and associated protein expression in cultured human umbilical vein endothelial cells. At 100 mg/l, both LDL species considerably increase apoptosis (LDL(iv) 63%, LDL(D) 40%; P < 0.05) compared with intraindividual nonglycated LDL subfractions. Considering its lower degree of glycation (LDL(D) 5-10%, LDL(iv) 42%), LDL(D)'s relative proapoptotic activity is 2.7-fold greater than that of LDL(iv). Glycated LDL-induced apoptosis is associated with increased expression of apoptosis promotors (LDL(iv): bak 88%, CPP-32 49%; LDL(D): bak 18%, CPP-32 11%; P < 0.05) and is attenuated by caspase inhibitors. Glycated LDL's antiproliferative activity (LDL(iv) -34%, LDL(D) -9%; P < 0.01) relates to reduction (P < 0.05) of cyclin D3 (LDL(iv) -27%, LDL(D) -24%) and of hypo- (LDL(iv) -22%, LDL(D) -19%) and hyperphosphorylated (LDL(iv) -53%, LDL(D) -22%) retinoblastoma protein and is paralleled by reduced expression of endothelial nitric oxide synthase (LDL(iv) -30%, LDL(D) -23%). In response to lipoprotein lipase, LDL(D) more markedly triggers endothelial apoptosis (27.1-fold) compared with LDL(iv), suggesting that LDL(D) owns a higher potential for endothelial cell damage than LDL(iv). The observed behavior of LDL(D) versus LDL(iv) could be of clinical importance and well relate to differences in structure and cellular uptake of LDL(D) compared with LDL(iv).

Modulation by leptin of proliferation and apoptosis in vascular endothelial cells

AIM

Plasma leptin concentrations not only correlate with body fat mass, but also with the degree of hypertensive retinopathy. The present study was designed to further examine, whether leptin's proliferative, proangiogenic activity relates to a yet uncovered anti-apoptotic effect.

RESULTS

Leptin (10-50 nmol/l) concentration-dependently reduced apoptosis in HUVECs (human umbilical vein endothelial cells), HAVECs (human adult vein endothelial cells) and HMECs (human microvascular endothelial cells) by 20% (P < or = 0.05). These findings were supported by increased expression of the apoptosis inhibitor bcl-2 (+55%, P < or = 0.05) as well as by differential modulation of the respective cell cycle checkpoint genes/proteins p53 (-20%, P < or = 0.01), p21(WAF-1/Cip1) (-23%, P < or = 0.05) and the Retinoblastoma protein (+123%, P < or = 0.01).

CONCLUSION

bcl-2 dependent anti-apoptotic action might contribute to leptin's proangiogenic activity and thereby promote the development of vascular proliferative disease in obesity.