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PubMed2006

Immunologic effects of mistletoe lectins: a placebo-controlled study in healthy subjects.

The subcutaneous application of lectin-rich mistletoe preparations such as Iscador Quercus (IQ; Weleda Company, Schwäbisch Gmünd, Germany) results in a peripheral eosinophilia. Our goal was to investigate whether this effect is related to mistletoe lectin (ML) and whether it is caused by a response of the specific immune system. In a double-blinded study, 43 volunteers were randomized to one of four treatment groups: (1) IQ, (2) ML that was derived from IQ, (3) IQ that was depleted of ML, and (4) placebo. The respective preparations were applied subcutaneously twice per week for 8 weeks, in increasing doses. Weekly the differential blood count was analyzed. Every 4 weeks interferon-gamma, interleukin-5 (IL-5), and granulocyte-macrophage colony stimulating factor (GM-CSF) were determined in cultures from peripheral mononuclear cells after stimulation with IQ. IQ and ML resulted in significant eosinophilia compared with placebo and ML-depleted IQ. Furthermore, the leukocyte and granulocyte counts were increased in the IQ and ML groups compared with placebo. GM-CSF, interferon-gamma, and IL-5 increased after ex vivo in vitro stimulation with IQ in the IQ and ML groups, and were significantly different from placebo in the IQ group but not in the ML group. Eosinophilia during therapy with mistletoe preparations is due to its content of ML. This effect might be related to a stimulation of IL-5 and/or GM-CSF, which was demonstrated ex vivo in vitro. ML resulted in a temporary increase of the granulocyte count, which is probably related to an acute-phase reaction.

Adult↗
PubMedDate not supplied

[The structure of toxic protein, the mistletoe lectin, at different pH: the study using intrinsic fluorescence method].

The effects of pH on the conformation of mistletoe lectin I and its isolated A- and B-subunits has been investigated by using the methods of intrinsic fluorescence. By the denaturating action of guanidine hydrochloride and the influence of the quenchers (I-, Cs+, acrylamide) the structural stability of the native protein and its isolated subunits was estimated. Treatment of the protein with the denaturant and quenchers revealed its different structure at pH 7.0 and 4.0. At pH 4.0 tryptophan residues become more accessible to quenchers, positive charge of the surrounding area increases and the protein becomes more stable to the action of denaturant. The structure of the isolated A- and B-chains of mistletoe lectin I differs considerably from that of the whole protein: a) its stability to the action of guanidine hydrochloride is lower; b) it depends on the ionic strength of the solvent; c) it is characterized by increased accessibility of tryptophan residues to quenchers (for B-chain). Differences between the conformations of the isolated chains at pH 7.0 and 4.0 are marked more strongly; moreover, at pH 4.5 the B-chain undergoes structural transition. The possible relationship between structural peculiarities of mistletoe lectin I and the mechanism of its transmembrane transfer is discussed.

Hydrogen-Ion Concentration↗
PubMed1996

Stimulation of neutropoiesis by a special standardized mistletoe preparation after cyclophosphamide chemotherapy in mice.

Lektinol, is a special mistletoe preparation (SMP) with immunostimulatory activity, standardized with respect to bioactive mistletoe lectin, one of the most active components of mistletoe. In the present study, stimulation of leukopoiesis by SMP was investigated in mice after induction of myelosuppression by the cytostatic agent cyclophosphamide (CP). Under the experimental conditions described, CP induced severe leukopenia followed by a recovery phase where leukopoiesis was distinctly enhanced in mice treated additionally with SMP at daily intravenous doses in a range of 30 to 5000 microliters/kg body weight. This phenomenon was mainly due to a stimulation of granulopoiesis resulting in a stronger increase of metamyelocyte and mature neutrophil counts in the peripheral blood.

Animals↗
PubMedDate not supplied

Further refinement of the description of the ligand-binding characteristics for the galactoside-binding mistletoe lectin, a plant agglutinin with immunomodulatory potency.

The galactoside-binding lectin from mistletoe (Viscum album L.) is a biological response modifier, eliciting e.g. enhanced secretion of cytokines. This immunological activity warrants the further analysis of its ligand-binding properties with special attention paid to blood group epitopes. To avoid the microheterogeneity and complexity of naturally occurring glycoproteins, chemically strictly defined neoglycoconjugates and a panel of synthetic oligosaccharides were employed in solid-phase assays for direct binding and assessment of the relative inhibitory capacity. Since label incorporation into the lectin, although performed under protective conditions, or surface immobilization by adsorption to plastic may affect its affinity characteristics, the extent of neoglycoconjugate binding in the absence of any interfering substance and in the presence of oligosaccharides was determined comparatively with labeled and with immobilized lectin. In principle, these two factors could be excluded to markedly alter binding features. In addition to lactose, the blood group determinants H and B were strongly reactive. A fucose residue can thus especially be accommodated to the binding site when linked to the non-reducing unit. N-Acetyllactosamine was nearly as potent as an inhibitor as lactose. Lec and the A determinant were notably inferior to the other ABH blood group epitopes. Le(a) and Le(x) and their sialylated derivatives displayed only very weak binding capacity. Among the two natural isomers of sialyllactose, the alpha 2,6-form displayed a higher level of inhibitory capacity than the alpha 2,3-derivative. Isomeric variants of the Thomsen-Friedenreich antigen, too, reduced lectin binding to the lactose-carrying polymer. Their capacities were surpassed by those of the H and the B determinants and a related form of the latter, the P1 epitope. An overlap of specificity with the immunomodulatory human galectin-3 is thus measurable for H/B-like structures. The documented differential reactivity of the mistletoe lectin to blood group oligosaccharides may have a bearing on the responsiveness of blood group-positive cell populations.

Adjuvants, Immunologic↗
PubMed2000

Comparative study of Korean (Viscum album var. coloratum) and European mistletoes (Viscum album).

A lectin (agglutinin, VCA) from Korean mistletoe (Viscum album L. coloratum) was isolated by affinity chromatograpy on a asialofetuin-Sepharose 4B. The molecular weights of A- and B-chains of VCA were differenf from those of VAAS. The VCA recognized the antibody of VAAs in the Western blot analysis and ELLA system. We also investigated the synergistic effects of the components in mistletoe by dividing the extract into different molecular weight fractions.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Mistletoe lectin induces apoptosis and telomerase inhibition in human A253 cancer cells through dephosphorylation of Akt.

Mistletoe lectin has been reported to induce apoptosis in different cancer cell lines in vitro and to show antitumor activity against a variety of tumors in animal models. We previously demonstrated the Korean mistletoe lectin (Viscum album var. coloratum, VCA)-induced apoptosis by down-regulation of Bcl-2 and telomerase activity and by up-regulation of Bax through p53- and p21-independent pathway in hepatoma cells. In the present study, we observed the induction of apoptotic cell death through activation of caspase-3 and the inhibition of telomerase activity through transcriptional down-regulation of hTERT in the VCA-treated A253 cells. We also observed the inhibition of telomerase activity and induction of apoptosis resulted from dephosphorylation of Akt in the survival signaling pathways. In addition, combining VCA with the inhibitors of phosphatidylinositol 3-kinase (PI3-kinase) upstream of Akt, wortmannin and LY294002 showed an additive inhibitory effect of telomerase activity. In contrast, the inhibitor of protein phosphatase 2A (PP2A), okadaic acid inhibited VCA-induced dephosphorylation of Akt and inhibition of telomerase activity. Taken together, VCA induces apoptotic cell death through Akt signaling pathway in correlated with the inhibition of telomerase activity and the activation of caspase-3. From these results, together with our previous studies, we suggest that VCA triggers molecular changes that resulting in the inhibition of cell growth and the induction of apoptotic cell death of cancer cells, which suggest that VCA may be useful as chemotherapeutic agent for cancer cells.

Apoptosis↗
PubMed1993

Comparison of properties of mistletoe lectin I A-chain and ricin B-chain conjugate with native toxins.

Chimeric toxin protein was prepared from the mistletoe lectin I A-chain and ricin B-chain by using the disulfide exchange reaction. Ricin and chimeric protein were indistinguishable in binding to immobilized asialofetuin in ELISA. Chimeric protein was more toxic to Jurkat cells than native mistletoe lectin I, but not so effective as native ricin. In the presence of NH4Cl, which enhances the toxicity of some toxins and immunotoxins, but does not influence ricin toxicity, both ricin and chimeric toxin had equal cytotoxic activity. The possibility is discussed that the ricin B-chain protects the ricin A-chain (RTA) from degradation during delivering RTA from the cell surface to the place where RTA is translocated into the cytosol.

Cell Line↗
PubMed1995

Inhibitory effect of Korean mistletoe (Viscum album coloratum) extract on tumour angiogenesis and metastasis of haematogenous and non-haematogenous tumour cells in mice.

We examined the inhibitory effect of an aqueous extract (referred to as KM-110) from Viscum album coloratum, a Korean mistletoe, on tumour metastasis produced by highly metastatic murine tumour cells, B16-BL6 melanoma, colon 26-M3.1 carcinoma and L5178Y-ML25 lymphoma cells, using experimental and spontaneous metastasis models in syngeneic mice. In experimental metastasis of B16-BL6 and colon 26-M3.1 cells, intravenous (i.v.) administration of KM-110 (100 micrograms/mouse) 1 day after tumour inoculation significantly inhibited lung metastasis of both tumour cells. The administration of KM-110 also exhibited a therapeutic effect on liver and spleen metastasis of L5178Y-ML25 lymphoma cells. Furthermore, in spontaneous metastasis of B16-BL6 melanoma cells, multiple administration of KM-110 into tumour-bearing mice resulted in significant inhibition of lung metastasis by tumour cells, as well as the suppressive activity to the growth of primary tumour. In in vivo analysis for tumour-induced angiogenesis, the i.v. administration of KM-110 suppressed tumour growth and inhibited the number of blood vessels oriented towards the tumour mass. In a bioassay, the culture supernatant (KM-110-treated medium) of murine peritoneal macrophages that had been stimulated with KM-110 (1-10 micrograms/ml) for 30 min followed by 24 h incubation in fresh medium showed a strong tumour necrosis factor-alpha (TNF-alpha) activity. In addition, KM-110-treated medium significantly inhibited the growth of in vitro cultures of rat lung endothelial (RLE) cells. These results suggested that the extract of Korean mistletoe inhibits tumour metastasis caused by haematogenous as well as non-haematogenous tumour cells, and that its antimetastatic effect results from the suppression of tumour growth and the inhibition of tumour-induced angiogenesis by inducing TNF-alpha.

Animals↗
PubMed2004

Purification and characterization of four isoforms of Himalayan mistletoe ribosome-inactivating protein from Viscum album having unique sugar affinity.

Ribosome-inactivating proteins having antitumor and immunomodulatory properties constitute the active principle of widely used mistletoe therapy in Europe. This is the first report of the four isoforms of Himalayan mistletoe ribosome-inactivating proteins (HmRips) from Viscum album parasitized on wild apple inhabiting NW Himalayas. HmRips were purified by affinity chromatography and four isoforms were separated by ion-exchange chromatography. HmRip 1, 2, 3, and 4 have isoelectric points of 6.6, 6.1, 5.2, and 4.7, respectively. Disulfide linked toxin and lectin subunits of HmRip 1 and 2 isoforms have molecular weights of 28 and 34kDa while those of HmRip 3 and 4 have 28 and 32kDa. The isoforms lacked blood group specificity and showed positive activity with seven mammalian erythrocyte types but did not show any activity with avian erythrocyte type. Lectin activity of HmRips remained unchanged for a wide range of temperatures (0-65 degrees C) and pH (3-9). Unlike other type II Rips, the HmRip 1, 2, and 4 showed unique affinity towards l-rhamnose, meso-inositol, and l-arabinose while HmRip 3 has specificity to gal/galNAc. Sugar binding studies with 22 sugars also suggested that the C-4 hydroxyl of galactose might be the critical site involved in sugar binding of HmRips. Type II Rips are known to be galactoside specific and do not have affinity for l-rhamnose and meso-inositol. However, HmRip 1, 2, and 4 having equal affinity for galactose and l-rhamnose do not strictly fit into any of the four structural classes of the lectins and represent a new class of type II Rips and plant lectins.

Amino Acid Sequence↗
PubMed2004

Differences in amino acid sequences of mistletoe lectin I and III B-subunits determining carbohydrate binding specificity.

Toxic lectins of European mistletoe Viscum album L.--MLI (viscumin), MLII and MLIII--are present in water extracts of this plant. Earlier we have cloned the full-length gene of MLIII precursor [A.G. Tonevitsky, I.I. Agapov, I.B. Pevzner, N.V. Maluchenko, M.M. Mojsenovich, U. Pfueller, M.P. Kirpichnikov, (2004) Biochemistry (Mosc.), 69 (6), 790-800, in press]. Here for the first time we report the cloning and expression in Escherichia coli cells of MLIII gene fragment encoding the carbohydrate-binding subunit. We have proved with our panel of monoclonal antibodies against ML toxins that the cloned fragment encoded MLIII B-subunit. The immunochemical and sugar-binding activities of renatured recombinant MLIII B-subunit were demonstrated in ELISA and ELLA, respectively. The comparative analysis of amino acid sequences of the cloned rMLIIIB and the B-subunits of other type II RIPs--MLI, ricin, abrin and nigrin b--was performed, revealing the main differences in primary structure of MLI and MLIII B-chains, which could determine their sugar specificity. The antigenicity analysis of MLI and MLIII B-subunits showed one epitope 25RDDDFRDGNQ34 in MLIB that is absent in MLIIIB sequence. The role of the toxic lectins and their subunits in immunological properties of mistletoe extracts is discussed.

Adjuvants, Immunologic↗
PubMed1996

Complete amino acid sequence of the A chain of mistletoe lectin I.

The complete amino acid sequence of the A chain of mistletoe lectin I was determined via Edman degradation sequencing of the N-terminus and tryptic and endoproteinase Asp-N overlapping fragments, amino acid analysis and MALDI-MS. The data obtained show a great homology with the chains of ribosome-inactivating proteins such as ricin and abrin with 111 (abrin-a) and 103 (ricin-D) amino acid residues conserved, respectively. The knowledge of the primary structure of MLA will have a fundamental impact on elucidating the biological function of medically applied mistletoe lectins on a molecular basis.

Amino Acid Sequence↗
PubMed1994

Binding patterns of mistletoe lectins I, II and III to microglia and Alzheimer plaque glycoproteins in human brains.

Glycoconjugates of microglial cells and in some cases those glycoconjugates present in the amyloid plaques in Alzheimer's disease in the cerebral cortex can be stained with a lectin from mistletoe (ML-I) using a labour-intensive and time-consuming indirect immunoperoxidase technique. In order to simplify the staining method and to test the staining characteristics of the other recently isolated mistletoe lectins (ML-II, ML-III) biotinylated MLs I-III were used together with an avidin-alkaline phosphatase-complex for visualisation. Our findings indicate that this new improved technique can also be used for detection of microglial cells and is considerably faster than the old method. In addition to microglial cells, ML-I labelled plaque glycoproteins possibly indicating that glycoconjugates derived from microglia can be detected in plaques. In contrast to ML-I, both ML-II and ML-III did not stain microglial cells.

Alzheimer Disease↗
PubMed1999

Cytotoxic effects of the components in heat-treated mistletoe (Viscum album).

Major cytotoxic components were fractionated from Korean mistletoe and the changes of their cytotoxic effects caused by heat treatment were investigated. The high cytotoxicity of isolated lectin I completely disappeared by heating for 30 min. The fractions of viscotoxins and alkaloids maintained their activities even after heating for 60 and 180 min, respectively. The alkaloid fraction was more cytotoxic to tumor MSV cells than to non-tumor A31 cells and the activity pattern was not changed by heat treatment. The possible contributions of alkaloids and viscotoxins to the activities of heat-treated mistletoe extracts such as tea or decoctions are discussed.

3T3 Cells↗
PubMed1998

Study of an Argentine mistletoe, the hemiparasite Ligaria cuneifolia (R. et P.) Tiegh. (Loranthaceae).

Ligaria cuneifolia (R. et P.) Tiegh. is an hemiparasite species used in Argentine folk medicine as a substitute for the European mistletoe (Viscum album L.) based on its putative activity of decreasing high blood pressure. This paper analyzes flavonoid composition, protein constituents and the possible immunomodulatory and antitumoral effects of this species. Micromolecular study disclosed quercetin-free, quercetin-glycosylated and proanthocyanidins corresponding to cyanidin monomers, which implies a particular metabolic pathway. Proteins present in L. cuneifolia extracts analyzed by SDS-PAGE presented multiple bands with molecular weights ranging from 14 to 90 kD. These features contribute to the characterization of the native mistletoe. As V. album is being used in cancer treatment due to its immunomodulatory and antitumoral activity, the action of aqueous L. cuneifolia extracts on murine lymphocytes was investigated. Culture of murine spleen cells alone or stimulated with Concanavalin A or lipopolysaccharide in presence of L. cuneifolia extracts indicated a certain stimulation of splenocytes alone and an inhibition of splenocytes stimulated with Concanvalin A or lipopolysaccharide. An inhibitory effect was also observed on the proliferation of murine leukemia cells. In addition, aqueous extracts increased nitric oxide production by murine macrophages. These results suggest that L. cuneifolia extracts exert an immunomodulatory effect on the mouse immune system.

Animals↗
PubMed1997

Lack of an antitumoral effect of immunomodulatory galactoside-specific mistletoe lectin on N-methyl-N-nitrosourea-induced urinary bladder carcinogenesis in rats.

The aim of the present animal experiment was to study the effect of galactoside-specific lectin or agglutinin (VAA) from mistletoe (Viscum album L.) on chemically induced tumor development in the urinary bladder of rats. Since VAA has been shown to exert a remarkable immunomodulating effect, any change in tumor formation would indicate a lectin-triggered immune control of urothelial carcinogenesis in the used model. To produce vesical neoplasms the direct-acting urothelial carcinogen N-methyl-N-nitrosourea (MNU) was administered at a single intravesical dose (7.5 mg/kg body weight). Highly purified VAA was given subcutaneously twice a week at the immunomodulatory dose of 1 ng/kg body weight over a period of 6 months during the critical phases of tumor development. After a total experimental time of 15 months the incidence of epithelial bladder tumors was 29.3% in controls versus 27.9% in rats additionally receiving the lectin and thus not significantly different in both experimental groups. There were, moreover, no substantial differences in the histopathologic spectrum of epithelial tumors induced, their patterns of growth, grades of cellular malignancy and local extension. The frequency and histopathology of mesenchymal bladder tumors as well as the incidence and morphology of carcinomas of the ureters and renal pelves also proved to be similar in controls and in rats treated with VAA. In conclusion, the present data provide no evidence for a modifying or even inhibitory effect of the immunomodulatory galactoside-specific mistletoe lectin on experimental urothelial carcinogenesis.

Adjuvants, Immunologic↗
PubMed1981

Isolation and properties of three lectins from mistletoe (Viscum album L.).

Three lectins have been isolated from an extract of mistletoe (Viscum album) by affinity chromatography on partially hydrolysed Sepharose and human immunoglobulin- Sepharose. The lectins differ in molecular weight and sugar specificity (lectin I, mol.wt. 11500, D-galactose-specific; lectin II, mol.wt. 60000, both D-galactose- and N-acetyl-D-galactosamine-specific; lectin III, mol. wt. 50000, N-acetyl-D-galactosamine-specific). All three lectins react with human erythrocytes without specificity for the A, B, and O blood groups. In contrast with abrin and ricin the mistletoe lectins cannot be divided into "toxins" and "haemagglutinins".

Carbohydrates↗
PubMed2002

Mistletoe viscotoxins increase natural killer cell-mediated cytotoxicity.

Mistletoe extracts have immunomodulatory activity. We show that nontoxic concentrations of Viscum album extracts increase natural killer (NK) cell-mediated killing of tumor cells but spare nontarget cells from NK lysis. The compounds responsible for this bioactivity were isolated from mistletoe and characterized. They have low molecular mass and are thermostable and protease-resistant. After complete purification by HPLC, they were identified by tandem MS as viscotoxins A1, A2 and A3 (VTA1, VTA2 and VTA3, respectively). Whereas micromolar concentrations of these viscotoxins are cytotoxic to the targets, the bioactivity with respect to NK lysis is within the nanomolar range and differs between viscotoxin isoforms: VTA1 (85 nm), VTA2 (18 nm) and VTA3 (8 nm). Microphysiometry and assays of cell killing indicate that, within such nontoxic concentrations, viscotoxins do not activate NK cells, but act on cell conjugates to increase the resulting lysis.

Antibody-Dependent Cell Cytotoxicity↗
PubMed2005

Exploratory study on the effects of treatment with two mistletoe preparations on chronic hepatitis C.

Twenty-one patients with chronic hepatitis C were treated with a mistletoe preparation as monotherapy (either Iscador or Abnoba viscum) during one year. The treatment was well tolerated. Patients entering the study with elevated transaminases had a significant improvement, both for AST (aspartate aminotransferase) (p = 0.01) and for ALT (alanine aminotransferase) (p = 0.04). Quality of life significantly improved (p = 0.006) in patients with a low initial quality of life. Although one patient obtained a complete virological response, few effects on viral load were seen in the whole group. These results suggest an effect comparable to glycyrrhicin treatment: improvement of liver inflammation and thus possibly reduction of the long term complications, viz cirrhosis and liver cancer. Mistletoe preparations have the advantage of easy administration and low cost.

Adult↗