Swainsonine stimulates bone marrow cell proliferation and differentiation in different strains of inbred mice

Swainsonine exposure induces impairment of host immune response in pregnant BALB/c mice

BACKGROUND

Swainsonine can cause serious disorders in reproduction of livestock, affecting both corpora lutea and reproductive hormone. The purpose of this study was to investigate the mechanisms of swainsonine about the immunotoxic effects on pregnant mice in vivo.

RESULTS

The peripheral Th1/Th2 was detected by Ionomycin and phorbol myristate acetate (PMA)-stimulating peripheral blood mononuclear cells (PBMC) of phase pregnant mice. Relevant cytokines in serum was evaluated after exposed to different dose of swainsonine. Gene expression of IL-1β, IFN-γ, TNF-α, IL-4 and IL-10 in PBMC was assessed by real-time PCR. Swainsonine caused vacuolization phenomenon of lutein cells and a dose-effect relationship. The IL-1β, IFN-γ and TNF-α were promoted, but IL-4 and IL-10 were suppressed in serum. Swainsonine significantly increased IL-1β, IFN-γ and TNF-α nuclear translocation and decreased IL-4 and IL-10. Swainsonine resulted in a significant shift of peripheral Th1/Th2 paradigm to Th1.

CONCLUSIONS

Our data demonstrate that the immunomodulatory of swainsonine disturbed the regular immunologic state of the pregnant mice. This may increase the risk of abortion and probably resulted in serious disorders in reproduction of livestock.

Pilocarpine-induced convulsive activity is limited by multidrug transporters at the rodent blood-brain barrier

As a result of the growing availability of genetically engineered mouse lines, the pilocarpine post-status epilepticus (SE) model of temporal lobe epilepsy is increasingly used in mice. A discrepancy in pilocarpine sensitivity in FVB/N wild-type versus P-glycoprotein (PGP)-deficient mice precipitated the investigation of the interaction between pilocarpine and two major multidrug transporters at the blood-brain barrier. Doses of pilocarpine necessary for SE induction were determined in male and female wild-type and PGP-deficient mice. Brain and plasma concentrations were measured following low (30-50 mg⋅kg(-1) i.p.) and/or high (200 mg⋅kg(-1) i.p.) doses of pilocarpine in wild-type mice, and mice lacking PGP, breast cancer resistance protein (BCRP), or both transporters, as well as in rats with or without pretreatment with lithium chloride or tariquidar. Concentration equilibrium transport assays (CETA) were performed using cells overexpressing murine PGP or BCRP. Lower pilocarpine doses were necessary for SE induction in PGP-deficient mice. Brain-plasma ratios were higher in mice lacking PGP or PGP and BCRP, which was also observed after pretreatment with tariquidar in mice and in rats. Lithium chloride did not change brain penetration of pilocarpine. CETA confirmed transport of pilocarpine by PGP and BCRP. Pilocarpine is a substrate of PGP and BCRP at the rodent blood-brain barrier, which restricts its convulsive action. Future studies to reveal whether strain differences in pilocarpine sensitivity derive from differences in multidrug transporter expression levels are warranted.

Simple Indolizidine and Quinolizidine Alkaloids

This review of simple indolizidine and quinolizidine alkaloids (i.e., those in which the parent bicyclic systems are in general not embedded in polycyclic arrays) is an update of the previous coverage in Volume 55 of this series (2001). The present survey covers the literature from mid-1999 to the end of 2013; and in addition to aspects of the isolation, characterization, and biological activity of the alkaloids, much emphasis is placed on their total synthesis. A brief introduction to the topic is followed by an overview of relevant alkaloids from fungal and microbial sources, among them slaframine, cyclizidine, Steptomyces metabolites, and the pantocins. The important iminosugar alkaloids lentiginosine, steviamine, swainsonine, castanospermine, and related hydroxyindolizidines are dealt with in the subsequent section. The fourth and fifth sections cover metabolites from terrestrial plants. Pertinent plant alkaloids bearing alkyl, functionalized alkyl or alkenyl substituents include dendroprimine, anibamine, simple alkaloids belonging to the genera Prosopis, Elaeocarpus, Lycopodium, and Poranthera, and bicyclic alkaloids of the lupin family. Plant alkaloids bearing aryl or heteroaryl substituents include ipalbidine and analogs, secophenanthroindolizidine and secophenanthroquinolizidine alkaloids (among them septicine, julandine, and analogs), ficuseptine, lasubines, and other simple quinolizidines of the Lythraceae, the simple furyl-substituted Nuphar alkaloids, and a mixed quinolizidine-quinazoline alkaloid. The penultimate section of the review deals with the sizable group of simple indolizidine and quinolizidine alkaloids isolated from, or detected in, ants, mites, and terrestrial amphibians, and includes an overview of the "dietary hypothesis" for the origin of the amphibian metabolites. The final section surveys relevant alkaloids from marine sources, and includes clathryimines and analogs, stellettamides, the clavepictines and pictamine, and bis(quinolizidine) alkaloids.

Increased sensitivity of Apolipoprotein E knockout mice to swainsonine dependent immunomodulation

The mechanisms that mediate accelerated atherosclerosis in autoimmune diseases remain unclear. One common mechanism that has been documented in autoimmune diseases and atherosclerosis is formation of hypoglycosyalted N-glycans on the cell surface. In this study we tested the effects of swainsonine, a class II α-mannosidase inhibitor which results in formation of hypoglycosylated N-glycans, on atherogenesis and immune cell dynamics in the atheroprone and hypercholesterolemic ApoE -/- mouse. Wild type or ApoE-/- mice (8 weeks of age) were fed a normal chow diet and administered swainsonine via the drinking water for 8 weeks at which time, atherosclerosis, and systemic markers of markers of inflammation were evaluated. Interestingly, no change in the rate of atherosclerosis development was observed in ApoE -/- mice treated with swainsonine. However, swainsonine significantly increased the number of peripheral blood leukocytes in ApoE -/- mice, with trends toward similar increases in swainsonine treated wild type mice noted. Assessment of leukocyte subsets using specific markers of all major blood lineages indicated that the increase in circulating leukocytes was due to the elevated number of progenitor cells. Consistent with swainsonine having a greater effect in ApoE -/- vs. wild type mice, increases in circulating inflammatory markers (IgA, IgG and chemokines) were observed in the former. Collectively, these data demonstrate that predisposition of ApoE -/- mice to vascular disease is associated with sensitization to the immunomodulatory effects of swainsonine and indicate that changes in N-glycans may provide a mechanism linking autoimmunity to atherogenesis.

The immunomodulatory effects of Ipomoea carnea in rats vary depending on life stage

Ipomoea carnea Jacq. ssp. fistulosa (Mart. Ex Choisy; Convolvulaceae; I. carnea) possesses a toxic component: an indolizidine alkaloid swainsonine (SW) that has immunomodulatory effects due to its inhibition of glycoprotein metabolism. It is also known that SW is excreted into both the amniotic fluid and milk of female rats exposed to I. carnea. Thus, the aim of this study was to determine whether SW exposure, either in utero or from the milk of dams treated with I. carnea, modulates offspring immune function into adulthood. In addition, adult (70 days old) and juvenile rats (21 days old) were exposed to I. carnea in order to evaluate several other immune parameters: lymphoid organs relative weight and cellularity, humoral and cellular immune responses. Offspring exposed to I. carnea during lactation developed rheumatoid arthritis (RA) in adulthood after an immunogenic challenge. In addition, both adult and juvenile rats exposed to I. carnea showed discrepancies in several immune parameters, but did not exhibit any decrease in humoral immune response, which was enhanced at both ages. These findings indicate that SW modulates immune function in adult rats exposed to SW during lactation and in juvenile and adult rats exposed to SW as juveniles and adults, respectively.

Increased antitumor efficacy by the combined administration of swainsonine and cisplatin in vivo

Swainsonine is a natural α-mannosidase inhibitor found in numerous poisonous plants, such as Astragalus lentiginosus. Its mechanism of action is through the inhibition of Golgi α-mannosidase II activity in the N-glycan biosynthesis pathway. As a result, swainsonine inhibits the production of complex β1,6-branched N-linked glycans, which are related to the malignant phenotype of tumor cells. In this study, we investigated whether treatment with swainsonine affects the sensitivity of Ehrlich ascites carcinoma (EAC) cells to cisplatin. To this end, male C57BL/6 mice were treated with swainsonine (SW--0.5 mg/kg, i.p., twice-daily for ten days) and/or cisplatin (Cis--0.25 mg/kg, i.p., every other day for a total of five applications) two days after transplantation with EAC cells. The results showed a greater reduction in the ascites volume in mice from the CisSW group (63.5%) than in mice from the Cis group (45.7%), an elevated induction of apoptosis by CisSW treatment when compared to Cis alone, as demonstrated by higher percentage of cells in the subG1 phase in that group (p<0.0001 Kruskal-Wallis, p<0.0001 control vs. CisSW, p<0.001 Co vs. Cis post-test Dunn), and an increase in the median survival from 12.5 days observed in the control group to 27 days in the CisSW group, which corresponds to a 116% survival increase (p=0.0022 Co vs. CisSW Log-rank test). In addition, the mice from the Cis group had a median survival of only 15 days, an increase of just 20% compared to controls. Our results indicate that swainsonine increases the sensitivity of EAC cells to cisplatin.

Suppressive effects of swainsonine on C6 glioma cell in vitro and in vivo

Swainsonine, an extract from Astragalus membranaceus, is known for its anti-cancer effects and could prevent metastases. In order to investigate the effects and mechanisms of swainsonine in C6 glioma cells, we carry out correlated experiments in vitro and in vivo. After treatment with swainsonine, the effective dose and IC(50) value of swainsonine in the C6 glioma cell were examined using the MTT assay. Cell cycle distribution and apoptotic rates were analyzed using FCM and [Ca(2+)](i) was measured by LSCM. Expressions of p16 and p53 protein were evaluated by immunocytochemical methods. Simultaneously, glioma-bearing rats were administered swainsonine at doses of 2, 4 and 8 mg/kg body wt. The inhibition rate was calculated and pathological sections were observed. The results indicated that the growth of C6 glioma cells is inhibited by swainsonine in vitro, with an IC(50) value within 24h of 0.05 microg/ml. Increases in swainsonine correlate with S phase percentages of 11.3%, 11.6% and 12.4%, respectively. Moreover, the expression of apoptosis inhibiting p53 and p16 protein decreases gradually. Tumor weight in vivo decreased clearly and HE dyeing of tumor tissue showed gray, its texture was soft, with necrosis and hemorrhagic concentrated inward. Swainsonine could inhibit the proliferation of C6 glioma cells in vitro and the growth of C6 glioma in vivo. The mechanisms of swainsonine-induced apoptosis may relate with the expression of apoptosis-related genes and overloading-[Ca(2+)](i)-induced endoplasmic reticulum stress.

General Approach to Glycosidase Inhibitors. Enantioselective Synthesis of Deoxymannojirimycin and Swainsonine

[reaction: see text] Deoxymannojirimycin (2) and swainsonine (4) have been synthesized from each enantiomer of the same bicyclic carbamate precursor 7. The key intermediate was prepared by a simple and efficient three-step synthesis involving RCM of the diene 8, which in turn is easily accessible in any configuration from enantiomerically enriched 2,3-epoxy-4-penten-1-ol 9.

Different adhesion and migration properties of human HCV29 non-malignant urothelial and T24 bladder cancer cells: role of glycosylation

In tumour cells, alterations in cellular glycosylation may play a key role in their metastatic behaviour. This study used cell lines having very different behaviour in vivo: HCV29 non-malignant transitional epithelium and T24 bladder transitional cell carcinoma. These differences in behaviour might be due in part to differences in cellular glycosylation patterns. Glycan chain analysis of their glycoproteins was performed with the use of specific lectins. The functional role of carbohydrates was studied by treating these cells with swainsonine, an inhibitor of Golgi alpha-mannosidase II, and in vitro adhesion and migration assays. The adhesion of swainsonine-treated HCV29 and T24 cells was increased on fibronectin and type IV collagen by 1.5- and 2-fold, respectively, whereas adhesion on laminin was virtually unchanged after swainsonine-treatment in HCV29 cells and was increased in T24 cells. Swainsonine treatment reduced the rate of T24 cell migration by 20%. We concluded that beta1-6 branched tri- and tetraantennary complex-type glycans have an important function in adhesion and migration in the studied cell lines. These data support the view that oligosaccharides are involved in several steps of the metastatic process.

Biomedical applications of poisonous plant research

Research designed to isolate and identify the bioactive compounds responsible for the toxicity of plants to livestock that graze them has been extremely successful. The knowledge gained has been used to design management techniques to prevent economic losses, predict potential outbreaks of poisoning, and treat affected animals. The availability of these compounds in pure form has now provided scientists with tools to develop animal models for human diseases, study modes of action at the molecular level, and apply such knowledge to the development of potential drug candidates for the treatment of a number of genetic and infectious conditions. These advances are illustrated by specific examples of biomedical applications of the toxins of Veratrum californicum (western false hellebore), Lupinus species (lupines), and Astragalus and Oxytropis species (locoweeds).

Synthesis of the New Mannosidase Inhibitors, Diversity-Oriented 5-Substituted Swainsonine Analogues, via Stereoselective Mannich Reaction

5alpha-substituted swainsonine analogues were synthesized by Mannich reaction of an in situ generated (-)-swainsonine iminium ion intermediate. 5alpha-substituted swainsonine analogues were epimerized to their 5beta-isomers in protic solvent. [reaction: see text]

Limits of stimulation of proliferation and differentiation of bone marrow cells of mice treated with swainsonine

The limits of stimulation of the immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) were studied in inbred C57BL/6 mice for potential support of intense high dose cancer chemotherapy and/or radiation because of its attractive pharmacologic profile on the hematopoietic system. Specifically, the effects of swainsonine on bone marrow cellularity and on in vitro progenitor cell proliferation to total colony forming units (CFU) and differentiation to different lineages were studied as a function of number of days post drug administration. The lineages evaluated were colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFU-e) and CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM or CFU-Mix). Groups of mice were treated with swainsonine or plain vehicle, phosphate buffered saline for 10 consecutive days. The effects of these agents on the hematopoietic system were studied up to 60 days following their discontinuation. The magnitude of the effects of swainsonine on bone marrow system gradually declined with increasing duration of days following its discontinuation. Nevertheless, its residual stimulatory effects on bone marrow cellularity, total CFU, CFU-GM, BFU-e and CFU-Mix continued to be significant (P<0.0001) up to 45, 50, 50, 55 and 50 days, respectively, compared to those of diluent buffer or untreated controls. Since cancer chemotherapeutic agents or radiation are normally given in schedules and/or cycles, these results strongly suggest that swainsonine effects are sustained long enough to potentially support and facilitate hematopoietic recovery during anti-cancer cytotoxic treatment.

Enhanced proliferation of functionally competent bone marrow cells in different strains of mice treated with swainsonine

The immunomodulatory alkaloid swainsonine (8alphabeta-indolizidine-1alpha,2alpha,8beta-triol) has potential for overcoming the bone marrow suppressive effects of cancer chemotherapy and radiotherapy. An earlier study showed that multiple doses of swainsonine enhanced bone marrow cellularity in four different strains (C57BL/6; C3H-HEN; Balb/C and DBA-2 mice) of inbred mice which were not exposed to any chemotherapeutic agents or radiation. In vitro assessment of total colony formation capacity of bone marrow cells (BM CFUs) showed a 2- to 8-fold increase in swainsonine-treated mice compared to control mice that were given sham injections of physiological saline. In the current study, we have evaluated the functional competence of the bone marrow cells produced in response to swainsonine treatment of normal healthy mice. In particular, colony forming units-granulocyte-macrophage (CFU-GM), erythroid-burst forming units (BFUe) and CFU-Mix (or CFU-granulocyte-erythrocyte-monocyte-megakaryocyte (CFU-GEMM)) levels, were determined using in vitro assays. The time course of the changes in CFU-GM, BFUe and CFU-Mix (CFU-GEMM) were also followed. Our results demonstrate that swainsonine bolsters the CFU capacity of BM cells without loss of function to levels which are several folds higher than in sham-treated control mice. Swainsonine treatment caused an increase in all lineages of marrow cells without loss of function. This effect was reproduced in all four strains of inbred mice in this investigation. Examination of the peripheral blood did not reveal increase in white blood cells or changes in the hematocrit levels. The long-term effects of swainsonine treatment are not known at present. Nonetheless, swainsonine-induced increase in CFU capacity of bone marrow cells and related cells along the different differentiation paths should find clinical application in cancer treatment with chemotherapeutic agents and/or radiation.