Modulation of the haematopoietic toxicity associated with zidovudine in vivo with lithium carbonate

The Effect of Lithium on Inflammation-Associated Genes in Lipopolysaccharide-Activated Raw 264.7 Macrophages

Lithium remains the preferred Food and Drug Administration- (FDA-) approved psychiatric drug for treatment of bipolar disorders since its medical establishment more than half a century ago. Recent studies revealed a promising role for lithium in the regulation of inflammation, oxidative stress, and neurodegeneration albeit unclear about its exact mode of action. Thus, the intention of this study is to delineate the regulatory mechanisms of lithium on oxidative stress in lipopolysaccharide- (LPS-) activated macrophages by evaluating its effects on nuclear factor-κB (NF-κB) activity and mRNA expression of multiple oxidative stress-related NF-κB genes. Raw 264.7 macrophages were treated with up to 10 mM lithium, and no change in cell proliferation, viability, growth, and cell adhesion was observed in real time. Pretreatment with low doses of lithium was shown to reduce nitric oxide (NO) production in LPS-activated macrophages. A reduced internal H₂DCFDA fluorescence intensity, indicative of reduced reactive oxygen species (ROS) production, was observed in LPS-activated Raw 264.7 macrophages treated with lithium. Lithium has been shown to lower the production of the chemokine RANTES; furthermore, this inhibitory action of lithium has been suggested to be independent of glycogen synthase kinase-3 β (GSK3β) activity. It is shown here that lithium modulates the expression of several inflammatory genes including IκB-α, TRAF3, Tollip, and NF-κB1/p50 which are regulators of the NF-κB pathway. Moreover, lithium inhibits NF-κB activity by lowering nuclear translocation of NF-κB in LPS-activated macrophages. This is the first study to associate Tollip, Traf-3, and IκB-α mRNA expression with lithium effect on NF-κB activity in LPS-activated Raw 264.7 macrophages. Although these effects were obtained using extratherapeutic concentrations of lithium, results of this study provide useful information towards understanding the mode of action of lithium. This study associates lithium with reduced oxidative stress in LPS-activated Raw 264.7 macrophages and further suggests candidate molecular targets for the regulation of oxidative stress-related diseases using lithium beyond bipolar disorders.

Lithium in the treatment of neutropenia

PURPOSE OF REVIEW

The capacity of lithium to induce neutrophilia and increase circulating CD34(+) cells of marrow origin has long been known. Lithium has been the object of hematological investigations for many years, but no definitive use in hematology has yet emerged.

RECENT FINDINGS

We review the evidence that lithium increases granulocyte colony-stimulating factor (G-CSF) and augments G-CSF effects, showing its potential use in stem cell mobilization and engraftment of stem cell transplantation.

SUMMARY

We suggest possible therapeutic uses of lithium in neutropenia. In bone marrow transplantation, preharvest lithium-assisted hematopoietic stem cell mobilization may be useful as well.

Zidovudine (AZT) treatment suppresses granulocyte-monocyte colony stimulating factor receptor type alpha (GM-CSFR alpha) gene expression in murine bone marrow cells

In vitro exposure of murine bone marrow cells to increasing concentrations of zidovudine (AZT, 0.1-50 microM) had a concentration dependent suppressive effect on the growth of granulocyte-monocyte colony forming unit (CFU-GM) derived colonies. In our previous published study, the mechanism of AZT-induced suppression of erythroid colony forming unit (CFU-E) derived colonies was linked to a decrease in erythropoitin receptor (Epo-R) gene expression. In this study, we have observed that AZT exposure also induced a concentration dependent suppressive effect (35-90%) on GM-CSF receptor type alpha (GM-CSFR alpha) gene expression. The suppression of GM-CSFR alpha mRNA expression was specific, since AZT caused a much lower decrease (15-22%) on the IL-3 receptor type alpha (IL-3R alpha) message level, and had an insignificant effect on glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and c-myc message levels. Erythropoietin (Epo) therapy has been used for reversal of AZT induced erythroid toxicity. Exposure to increasing concentrations (10-500 U/ml) of GM-CSF was unable to override the suppressive effect of AZT on CFU-GM derived colonies, however, treatment in combination with IL-3 (10-250 U/ml) ameliorated the suppressive effects of AZT on CFU-GM and on GM-CSFR alpha and IL-3R alpha gene expression. These findings suggest a mechanism via which AZT may suppress granulocyte-monocyte specific differentiation in murine bone marrow cells. These data also suggest that a combination of GM-CSF and IL-3 may be a superior therapeutic intervention for AZT-induced neutropenia.

Inhibition of beta-globin gene expression by 3'-azido-3'-deoxythymidine in human erythroid progenitor cells

3'-Azido-3'-deoxythymidine (AZT) treatment in HIV-infected patients is limited by bone marrow suppression including neutropenia and anemia. Previous studies had shown a direct effect of high concentrations of this drug on globin gene expression in K-562 erythroleukemia cells. To better define the mechanism(s) of AZT-induced bone marrow toxicity, the present study evaluates these effects in more relevant human erythroid progenitor liquid cultures, because AZT is 100 times more toxic to human bone marrow cells than K-562 cells. At a clinically relevant concentration of 1 microM, AZT inhibited specifically erythroid cell growth by approximately 58% as compared with untreated cells. The percentage of cells synthesizing hemoglobin was decreased also by 47% in AZT-treated cells with beta-globin mRNA levels accounting for 0.27 pmol in treated cells as compared with 1.44 under control conditions while beta-actin levels remained unchanged. Under the same conditions, AZT inhibited the beta-globin chain synthesis by approximately 60% as compared with the control. Consistent with the data described above was the finding that a concentration as low as 0.1 microM of AZT decreased by almost 40% the binding level of the erythroid-specific transcription factor GATA-1. These findings demonstrate that AZT, at clinical relevant concentrations, specifically inhibits beta-globin gene expression in human erythroid progenitor liquid cell culture.

Effects of psychotropic drugs on cell proliferation and differentiation

Some of the psychotropic agents widely used for the amelioration of anxiety, depression, and psychosis also show an effect at the cellular proliferation level. Surprisingly little research, however, has been directed to the antitumoral potential of these drugs, alone or in combination with established cancer treatments. Our review of the literature to date has yielded some promising early findings. Ligands active at the benzodiazepine (BZ) receptors have been studied the most extensively and were found to have differential, concentration-dependent effects on the growth and proliferation of both normal and cancer cells. Of the phenothiazines tested, chlorpromazine (CPZ) and perphenazine (PPZ) had the most potent cytotoxic action on fibroblasts and glioma cells. Antiproliferative effects also were noted by these and other agents in leukemic and breast cancer cell lines. Additional psychotropic drugs studied include the atypical antipsychotics, antidepressants, and mood stabilizers, especially lithium. Most of the reported activities were observed in in vitro studies and were achieved at high pharmacological concentrations. Further in vivo studies in well-designed animal models are warranted to determine whether these well-tolerated, relatively inexpensive, and widely available drugs or their derivatives may be added in the future to the armamentarium of cancer pharmacotherapy.

The uptake of Li+ into human 1321 N1 astrocytomas using 7Li NMR spectroscopy

The uptake of Li+ ions into human 1321 N1 astrocytomas cultured on the surface of microcarrier beads was followed by 7Li NMR spectroscopy. The intracellular and extracellular 7Li resonances were separated by the use of dysprosium tripolyphosphate as a shift reagent. Excellent spectra were obtained from which the uptake of Li+ was found to be approximately ten times faster than that into human erythrocytes using the same technique and a steady-state intracellular Li+ concentration was observed within 60 min. The low intracellular Li+ concentration attained, relative to the extracellular concentration, indicates the presence of an efflux mechanism in astrocytomas that actively transports Li+ against its concentration gradient. The intracellular volume was estimated by quantitative 23Na NMR spectroscopy and the viability of the cells was confirmed by 31P NMR spectroscopy.

Effect of combination interleukin-3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) on hematopoiesis administered to retrovirus-infected immunodeficient mice receiving dose-escalation zidovudine (AZT)

We have previously demonstrated that continuous administration of dose-escalation zidovudine (AZT) in either normal or LP-BM5 MuLV immunodeficient virus-infected mice (MAIDS) was associated with the development of anemia, neutropenia, and thrombocytopenia. Hematopoietic growth factors/cytokines are being evaluated to determine their efficacy in ameliorating the hematopoietic toxicity associated with AZT. In normal mice receiving AZT, an increase in only plasma erythropoietin and not GM-CSF, Meg-CSF or TNF-alpha has been reported. This article describes studies that investigated the effect of combination interleukin-3 (IL-3) and granulocyte-macrophage colony stimulating factor (GM-CSF) administered in normal non-viral, viral-infected, and viral-infected C57BL6 mice receiving dose-escalation AZT, i.e. 0.1 mg/ml, 1.0 mg/ml, and 2.5 mg/ml placed in the drinking water. Non-viral control mice responded to IL-3/GM-CSF by increasing erythropoiesis, myelopoiesis and platelet production measured by increased bone marrow and spleen derived erythroid, myeloid and platelet precursor stem cells cultured in semi-solid media. Virus-infected control mice not receiving IL-3/GM-CSF developed pancytopenia. Administration of IL-3/GM-CSF to virus-infected mice receiving dose-escalation AZT did not ameliorate the peripheral pancytopenia associated with immunodeficiency disease and AZT treatment, even though erythroid, myeloid and platelet precursor progenitor cells were increased at certain times when compared to either normal or viral-infected mice receiving IL-3/GM-CSF. These results indicate that the combination use of IL-3 and GM-CSF in vivo is only a partially effective growth factor/cytokine treatment to ameliorate the hematopoietic toxicity associated with the use of the anti-viral drug zidovudine.

Influence of human granulocyte-macrophage colony stimulating factor/interleukin-3 fusion protein (PIXY321) on the hematopoietic toxicity associated with anti-viral drugs (zidovudine and didanosine) in vitro using normal human marrow cells

The antiviral drugs didanosine (ddI) and zidovudine (AZT), synthetic nucleoside analogs, have been used in the treatment of acquired immunodeficiency syndrome (AIDS). Although clinical use of zidovudine (AZT) is still widely used, it is associated with the development of virus disease resistance and toxicity to the hematopoietic system. Alternative nucleoside reverse transcriptase derivatives such as didanosine (ddI) have been developed in order to reduce the incidence of virus disease resistance and hematological toxicity. We report here studies designed to ev evaluate the toxicity profile comparing didanosine (ddI) with zidovudine (AZT) when used alone or in combination with normal non-adherent, T-cell depleted human marrow cells plated in the presence or absence of the human cytokine fusion protein of granulocyte-macrophage colony stimulating factor and interleukin-3 (PIXY321). As expected, didanosine (ddI) was less toxic for human hematopoietic progenitor cells, i.e., CFU-GEMM, CFU-GM, CFU-Meg, and BFU-E than zidovudine. Toxicity was additive when didanosine (ddI) and zidovudine (AZT) were combined. In the absence of drugs PIXY321 colony formation was increased for all progenitor cells cultured. In the presence of didanosine (ddI) or zidovudine (AZT), either as single-agents or combined, PIXY321 reduced toxicity significantly. These results demonstrate PIXY321 is an effective cytokine capable of reversing the toxicity associated with anti-viral drugs when used in vitro where didanosine (ddI) is less toxic than zidovudine (AZT); however their suppression of hematopoietic progenitors is additive when combined.

Effect of lithium in immunodeficiency: improved blood cell formation in mice with decreased hematopoiesis as the result of LP-BM5 MuLV infection

Lithium salts have been demonstrated to induce the production of hematopoietic cells following administration in vivo and to minimize the reduction of these cells following treatment with either radiation, chemotherapeutic or antiviral drugs. We have previously demonstrated that lithium, when administered in vivo to immunodeficient mice infected with LP-BM5 MuLV (MAIDS) significantly reduced the development of lymphadenopathy, splenomegaly, and the lymphoma associated with late-stage immunodeficiency disease in this model, and increased the survival of these animals compared to virus-infected controls not receiving lithium. We report here the results of in vivo studies in the MAIDS model that determined the effect of lithium on peripheral blood indices and the number of myeloid (CFU-GM), erythroid (BFU-E) and megakaryocyte (CFU-Meg) hematopoietic progenitors from bone marrow and spleen harvested from immunodeficient mice receiving lithium carbonate (1 mM) placed in their drinking water compared to virus-infected controls not receiving lithium. Time-points evaluated were at weeks 1, 5, 9, 13, 17, and 21 postviral infection. Virus-control mice not receiving lithium demonstrated all the signs that are characteristic of MAIDS, i.e., splenomegaly, lymphadenopathy, hypergammaglobulinemia, reduced hematopoiesis, and death. Infected mice receiving lithium demonstrated diminished presence of splenomegaly, lymphadenopathy, hypergammaglobulinemia, no suppression of hematopoiesis nor mortality. Enhanced hematopoiesis was demonstrated by neutrophilia, lymphocytosis, thrombocytosis, and erythrocytosis that was evident by increased myeloid, erythroid, and megakaryocyte progenitor cells cultured from bone marrow and spleen. These studies further demonstrate that lithium influences the disease process in the MAIDS model and restricts the development of hematopoietic suppression that develops in this retroviral animal model of immunodeficiency.