3,4-Dihydroxy-benzohydroxamic acid (Didox) suppresses pro-inflammatory profiles and oxidative stress in TLR4-activated RAW264.7 murine macrophages

Didox (3,4-dihydroxy-benzohydroxamic acid), is a synthetic ribonucleotide reductase (RR) inhibitor derived from polyhydroxy-substituted benzohydroxamic acid, and originally developed as an anti-cancer agent. Some studies indicate that didox may have anti-oxidative stress-like properties, while other studies hint that didox may have anti-inflammatory properties. Using nitric oxide production in response to LPS treatment as a sensitive screening assay for anti-inflammatory compounds, we show that didox is very potent at levels as low as 6.25 μM, with maximal inhibition at 100 μM. A qRT-PCR array was then employed to screen didox for other potential anti-inflammatory and anti-oxidative stress-related properties. Didox was very potent in suppressing the expression of these arrayed mRNA in response to LPS, and in some cases didox alone suppressed expression. Using qRT-PCR as a follow up to the array, we demonstrated that didox suppresses LPS-induced mRNA levels of iNOS, IL-6, IL-1, TNF-α, NF-κβ (p65), and p38-α, after 24h of treatment. Treatment with didox also suppresses the secretion of nitric oxide, IL-6, and IL-10. Furthermore, oxidative stress, as quantified by intracellular ROS levels in response to macrophage activators LPS and phorbol ester (PMA), and the glutathione depleting agent BSO, is reduced by treatment with didox. Moreover, we demonstrate that nuclear translocation of NF-κβ (p65) in response to LPS is inhibited by didox. These findings were supported by qRT-PCR for oxidative stress genes SOD1 and catalase. Overall, this study supports the conclusion that didox may have a future role in managing acute and chronic inflammatory diseases and oxidative stress due to high production of ROS.

Allied health professionals with 2020 vision

Allied health professionals in all disciplines must be visionary as they address education, training, and health care delivery in the next decade. Examined herein are forces of change in education, training, health care, the recognition of essential leadership styles, and the paradigm shifts facing the allied health profession in the health care arena. Some visionary directions are offered for allied health professionals to consider as health policy and clinical agendas emerge toward the year 2020.

Oxygen carriers: A selected review

The most common and widely transplanted tissue world wide is blood, which in 2000 resulted in the transfusion of 12.5 million units of blood in the US alone [Goodnough LT, Shander A, Brecher ME. Transfusion medicine: looking to the future. Lancet 2003;361:161-9]. The current use of donated blood products is relatively safe; however, there are inherent problems with allogeneic blood transfusions. The wide spread use of blood in procedures results in problems involving inadequate supply exacerbated in times of war and disasters and by the limited storage life of blood donations (30-42 days). Blood contamination due to patient pre-disposition, poor collection, sterilization, or storage is the second most common cause of death from transfusion in the US [Hillyer CD, Josephson CD, Blajchman MA, Vostal JG, Epstein JS, Goodman JL. Bacterial contamination of blood components: risks, strategies, and regulation: joint ASH and AABB educational session in transfusion medicine. Hematology (Am Soc Hematol Educ Program) 2003:575-89]. Blood is a complex tissue involved in a plethora of homeostatic roles, including immunity, wound healing and the transport of nourishment, electrolytes, hormones, vitamins, heat, oxygen and the removal of metabolic waste products. However, by far the principle role of blood transfusions is the replacement of red cell volume and the maintenance of oxygen levels within the circulation. Creation of investigational new drugs (INDs) which would function as oxygen carriers and prolong shelf life is now a very active arena of scientific research. Several such IND products are now in clinical trials. This article gives an easy to follow concise evaluation of major areas of focus and current testing for each type of blood substitution molecule.

Cerebral excitability and the mechanisms of blood transportation of sodium

The basic, fundamental property of living structures is excitability. This process defines how an organism responds to both internal and external stimuli. Previous studies have indicated the existence of physical and chemical interactions between cations and anions sites of proteins within the extracellular environment that have a specific functional importance. However, it is not well understood whether specific cations may alter the function of specific proteins. We report here the results of studies that indicate interaction of specific cations such as sodium may alter the physico-chemical action of heparin. The importance of these interactions is discussed.

Reconstitution of erythroid, megakaryocyte and myeloid hematopoietic support function with neutralizing antibodies against IL-4 and TGFbeta1 in long-term bone marrow cultures infected with LP-BM5 murine leukemia virus

Murine acquired immunodeficiency syndrome (MAIDS) induced by a defective LP-BM5 murine leukemia virus (MuLV) produces hematopoietic cytopenias similar to HIV in patients with AIDS. The pathogenesis of MAIDS induced cytopenias remains obscure; however, direct retroviral infection of bone marrow stroma has been implicated to play a role. To evaluate the consequential effect of viral infection, primary stromal cell cultures were transiently incubated in vitro with LP-BM5 MuLV viral supernatant. Reverse transcription polymerase chain reaction (RT-PCR) and Southern blot hybridization revealed that defective LP-BM5 MuLV infection resulted in elevated levels of IL-4 and TGFbeta1 transcript expression in infected stromal cells. The increased expression of both IL-4 and TGFbeta1 transcripts was associated with enhanced production of corresponding proteins as determined by quantitative western blot analyses. Hematopoietic reconstitution assays revealed that the hematopoietic support function of stromal cells was significantly reduced following transient exposure to LP-BM5 MuLV. The production of nonadherent mononuclear cells and the growth of myeloid, megakaryocyte and erythroid lineages were all suppressed in infected cultures. Culture supernatant conditioned by infected stromal cells demonstrated growth-inhibitory activity for hematopoietic progenitor colony formation. This growth-inhibitory activity could be significantly abolished by addition of anti-IL-4 and/or anti-TGFbeta1 neutralizing antibodies to the culture supernatant or directly to the stromal cell cultures. This study demonstrates LP-BM5 MuLV increases two known cytokines to suppress hematopoiesis implicating viral infection can directly suppress hematopoiesis mediated by inhibitors released from marrow stroma.

Combination of inhibitors of lymphocyte activation (hydroxyurea, trimidox, and didox) and reverse transcriptase (didanosine) suppresses development of murine retrovirus-induced lymphoproliferative disease

The ribonucleotide reductase inhibitor hydroxyurea (HU) has demonstrated some benefit as a component of drug cocktails for the treatment of HIV-1 infection. However, HU is notoriously myelosuppressive and often administered only as salvage therapy to patients with late-stage disease, potentially exacerbating the bone marrow toxicity of HU. In this report we have compared the antiviral effects of HU and two novel RR inhibitors trimidox (3,4,5-trihydroxybenzamidoxime) and didox (3,4-dihydroxybenzohydroxamic acid) in combination with didanosine (2,3-didoxyinosine; ddI) in the LPBM5 MuLV retrovirus model (murine AIDS). We also evaluated the effects of these drug combinations on the hematopoietic tissues of LPBM5 MuLV-infected animals. The combination of RR inhibitors and ddI was extremely effective (DX>TX>HU) in inhibiting development of retrovirus-induced disease (splenomegaly, hypergammaglobulinemia, activated B-splenocytes and loss of splenic architecture). In addition, relative levels of proviral DNA were significantly lower in combination drug-treated animals compared to infected controls. Evaluation of femur cellularity, numbers of marrow-derived myeloid progenitor cells (CFU-GM and BFU-E) and peripheral blood indices revealed that TX and DX in combination with ddI were well-tolerated. However, treatment with HU and ddI induced moderate myelosuppression. These data demonstrate that RR inhibitors in combination with ddI provide significant protection against retroviral disease in murine AIDS. Moreover, the novel RR inhibitors TX and DX appear to be more effective and less myelosuppressive than HU when administered with ddI in this model.

In vivo examination of hydroxyurea and the novel ribonucleotide reductase inhibitors trimidox and didox in combination with the reverse transcriptase inhibitor abacavir: suppression of retrovirus-induced immunodeficiency disease

Inhibition of ribonucleotide reductase (RR) has gained attention as a potential strategy for HIV-1 therapy through the success of hydroxyurea (HU) to potentiate the activity of the nucleoside reverse transcriptase inhibitor (NRTI) didanosine (ddI) in clinical trials. However, the use of HU has been limited by its development of hematopoietic toxicity. In this study, the novel RR inhibitors didox (DX; 3,4-dihydroxybenzohydroxamic acid), and trimidox (TX; 3,4,5-trihydroxybenzamidoxime) were evaluated along with HU for anti-retroviral efficacy in LPBM5-induced retro-viral disease (MAIDS) both as monotherapeutic regimens and in combination with the guanine containing NRTI abacavir (ABC). Anti-retroviral drug efficacy was determined by measuring inhibition of splenomegaly, hypergammaglobulinemia, and splenic levels of proviral DNA. In this study, all RRIs tested showed the ability to improve the efficacy of ABC in the MAIDS model by reducing splenomegaly, hypergammaglobulinemia, and splenic proviral DNA levels.

Basic fibroblast growth factor (bFGF) and its receptor expression (bek and flg) In bone marrow stroma of murine AIDS

Murine acquired immunodeficiency disease (MAIDS) induced by LPBM5 MuLV is characterized by a late-stage lymphoma and hematopoietic cytopenias similar to those observed in human AIDS. The pathogenesis of MAIDS-related lymphoma/cytopenia is unknown but it has been postulated to involve a defective marrow microenvironment or stroma. The basic Fibroblast Growth Factor (bFGF) of stromal origin is an important stimulator for hematopoietic progenitors of several lineages. Long-term bone marrow cultures (LTBMCs) were established and pure stromal cell cultures were used for in vitro infection hematopoietic reconstitution studies. Reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze bFGF gene expression in stromal cells derived from either viral-infected marrow or uninfected marrow. RT-PCR analysis showed a 40% reduction in the expression of bFGF transcript expression from viral-infected stromal cells, however, the levels of bek and flg bFGF receptors remained unchanged indicating virus-infection only inhibited bFGF gene expression in stromal cells. Viral infection was associated with a progressive decrease in bFGF transcript expression 35% of control at day 7, 50% of control at day 14 and 60% of control at day 21 compared to the mock-infected cultures. In addition, for bek and flg the transcript expression in, in vitro-infected primary cultures were comparable to the mock-infected cultures and remained essentially unchanged throughout culture period. Western blot analysis revealed viral-infected stromal cells produced a 45% decrease in bFGF protein production. Reduction of bFGF protein was confirmed by indirect immunofluorescent staining. We report MuLV infection reduces bFGF transcript expression but not its surface-receptors (bek and flg) in infected stromal cells. Impaired hematopoiesis consistently exhibited from MuLV-infected stromal cultures was restored by exogenous bFGF; therefore, bFGF was responsible in restoration of normal marrow stromal support function. These results suggest a role for bFGF deficiency in the pathogenesis of MAIDS-related marrow failure.

Farnesyltransferase inhibitor (L-744,832) restores TGF-beta type II receptor expression and enhances radiation sensitivity in K-ras mutant pancreatic cancer cell line MIA PaCa-2

Activated ras is known to dysregulate TGF-beta signaling by altering the expression of TGF-beta type II receptor (RII). It is well documented that tumor cells harboring mutant ras are more resistant to radiation than cells with wild-type ras. In this study, we hypothesized that the use of farnesyltransferase inhibitor (FTI, L-744,832) may directly restore TGF-beta signaling through RII expression via ras dependent or independent pathway leading to induction of radiation sensitivity. Two pancreatic cancer cell lines, BxPC-3 and MIA PaCa-2 were used in this study. FTI inhibited farnesylation of Ras protein more significantly in MIA PaCa-2 than BxPC-3 cells. In contrast, MIA PaCa-2 cells were resistant to radiation when compared to BxPC-3 cells. BxPC-3 cells were more resistant to FTI than MIA PaCa-2 cells. In combination treatment, no significant radiosensitizing effect of FTI was observed in BxPC-3 cells at 5 or 10 microM. However, in MIA PaCa-2 cells, a significant radiosensitizing effect was observed at both 5 and 10 microM concentrations (P>0.004). The TGF-beta effector gene p21(waf1/cip1) was elevated in combination treatment in MIA PaCa-2 but not in BxPC-3 cells. In MIA PaCa-2 cells, FTI induced TGF-beta responsive promoter activity as assessed by 3TP-luciferase activity. A further induction of luciferase activity was observed in MIA PaCa-2 cells treated with radiation and FTI. Induction of TGF-beta signaling by FTI was mediated through restoration of the RII expression, as demonstrated by RT-PCR analysis. In addition, re-expression of RII by FTI was associated with a decrease in DNA methyltransferase 1 (DNMT1) levels. Thus, these findings suggest that the L-744,832 treatment restores the RII expression through inhibition of DNMT1 levels causing induction of TGF-beta signaling by radiation and this forms a novel molecular mechanism of radiosensitization by FTI.

Suppression of retrovirus-induced immunodeficiency disease (murine AIDS) by trimidox and didox: novel ribonucleotide reductase inhibitors with less bone marrow toxicity than hydroxyurea

Recently, the use of the ribonucleotide reductase (RR) inhibitor hydroxyurea (HU) in combination with nucleoside analogs has gained attention as a potential strategy for anti-HIV-1 therapy. However, appeal for the long-term use of HU in HIV-1 infection may be limited by its propensity to induce hematopoietic toxicity. We report a comparison of the efficacy and bone marrow toxicity of HU (400 and 200 mg/kg/day) with the novel RR inhibitors and free radical-scavenging compounds didox (DX; 3,4-dihydroxybenzohydroxamic acid; 350 mg/kg/day) and trimidox (TX; 3,4,5-trihydroxybenzamidoxime; 175 mg/kg/day) in the murine AIDS (LPBM5 MuLV) model of retrovirus infection. Infected mice received daily drug treatment for 8 weeks. Efficacy was determined by measuring drug effects on retroviral-induced disease progression (i.e. development of splenomegaly and hypergammaglobulinemia) and by evaluating splenic levels of proviral DNA. Bone marrow toxicity was evaluated by measuring peripheral blood indices (WBC, hematocrit and reticulocyte counts), femoral cellularity and by determining the numbers of hematopoietic progenitor cells (CFU-GM, BFU-E) per femur and spleen. Compared to infected controls receiving no drug treatment, disease progression was significantly suppressed by TX, DX and HU. However, HU was associated with mortality and induced significant hematopoietic toxicity in a time- and dose-dependent manner. Conversely, TX and DX effectively inhibited retrovirus-induced disease but did not induce hematopoietic toxicity. These results suggest that due to their reduced hematopoietic toxicity and ability to inhibit disease progression in murine AIDS, TX and DX may offer effective alternatives to HU therapy in HIV-1 infection.

Didox (a novel ribonucleotide reductase inhibitor) overcomes Bcl-2 mediated radiation resistance in prostate cancer cell line PC-3

In this study, we investigated the influence of Bcl-2 overexpression on the radiosensitizing potential of Didox (DX; 3,4-Dihydroxybenzohydroxamic acid), a novel ribonucleotide reductase inhibitor, in p53-null prostate cancer cell line PC-3. The PC-3 cells were transfected with vector alone or ectopically overexpressed with CMV-Bcl-2 construct. The effect of radiation (IR) or DX alone and in combination (pre and post IR exposure of DX) on cell survival was determined by colony-forming assay. The impact of these two treatments on the cell cycle was determined by flow cytometry. To further understand the molecular mechanism of DX-mediated radiosensitization, induction of pro-survival and pro-apoptotic factors were determined by Western blot and gel-shift assays respectively. When compared to PC-3/Bcl-2 cells (SF(2)=0.84; D(0)=437cGy), the PC-3/vector cells (SF(2)=0.4; D(0)=235cGy) were significantly sensitive to ionizing radiation (p<0.001). Exposure of DX at 5 microM concentration prior or post to radiation in both PC-3/vector and PC-3/Bcl-2 transfectants caused an increase in radiation enhancement ratios. A significant reduction in G(2)M phase was observed in cells exposed to DX post IR when compared to cells exposed to IR alone. Exposure to DX after radiation in PC-3/vector significantly abrogated radiation-induced Bcl-2 upregulation, with a concomitant induction of bax protein. In PC-3/Bcl-2 transfectants, DX exposure after IR caused an induction of bax protein. Gel shift assays indicated that in PC-3/vector cells when exposed to IR caused an induction of NFkappa-B activity however, DX down regulated the NFkappa-B activity. Radiation-induced NFkappa-B activity was abrogated in pre and post DX exposure in combination with IR. These findings indicate that DX mediates a potent radiosensitizing effect in p53 null prostate cancer cells by overcoming radiation induced NFkappa-B activity and Bcl-2 expression.

Short-term treatment with novel ribonucleotide reductase inhibitors Trimidox and Didox reverses late-stage murine retrovirus-induced lymphoproliferative disease with less bone marrow toxicity than hydroxyurea

We evaluated the ability of a short course of treatment with the ribonucleotide reductase (RR) inhibitor hydroxyurea (HU) and two novel RR inhibitors Trimidox (TX) and Didox (DX) to influence late-stage murine retrovirus-induced lymphoproliferative disease. LPBM5 murine leukaemia virus retrovirus-infected mice were treated daily with HU, TX or DX for 4 weeks, beginning 9 weeks post-infection, after development of immunodeficiency and lymphoproliferative disease. Drug effects on disease progression were determined by evaluating spleen weight and histology. Effects on haematopoiesis were determined by measuring peripheral blood indices (white blood cells and haematocrit) and assay of femur cellularity and femoral and splenic content of colony-forming units granulocyte-macrophage (CFU-GM) and burst-forming units-erythroid (BFU-E). HU, TX and DX partially reversed late-stage retrovirus-induced disease, resulting in spleen weights significantly below pre-treatment values. Spleen histology was also improved by RR inhibitor treatment (DX>TX>HU). However, as expected, HU was significantly myelosuppressive, inducing a reduction in peripheral indices associated with depletion of femoral CFU-GM and BFU-E. In contrast, although TX and DX were moderately myelosuppressive, both drugs were significantly better tolerated than HU. In summary, short-term treatment in late-stage murine retroviral disease with HU, TX or DX induced dramatic reversal of disease pathophysiology. However, the novel RR inhibitors TX and DX had more effective activity and significantly less bone marrow toxicity than HU.

Low dose fractionated radiation enhances the radiosensitization effect of paclitaxel in colorectal tumor cells with mutant p53

BACKGROUND

The current study was undertaken to investigate the influence of wild-type or mutant p53 status on the radiosensitizing effect of paclitaxel in colorectal tumor cell lines.

METHODS

HCT-116 (contains wild-type p53) and HT-29 (contains mutant p53) established from moderately differentiated colorectal carcinomas were used in this study. Colony-forming assay was performed after exposure to either different radiation doses (0.5-6 gray [Gy]) or paclitaxel (1-10 nM) or in combination. Induction of p53 and p21(waf1/cip1) by these treatments were determined by immunocytochemistry and Western blot analysis.

RESULTS

Radiation caused an increase in nuclear p53 and p21(waf1/cip1) proteins in HCT-116 cells, indicating that p53 functionally induced p21(waf1/cip1). However, induction of nuclear p53 and p21(waf1/cip1) protein was not evident in HT-29 cells, suggesting that p53 was not functional in these cells. Survival data showed that the HCT-116 cells (survival fraction of exponentially growing cells that were irradiated at the clinically relevant dose of 2 Gy [SF(2)] = 0.383; dose required to reduce the fraction of cells to 37% [D(0)] = 223 centigray [cGy]) were significantly sensitive to ionizing radiation (P < 0.008) when compared with the HT-29 cells (SF(2) = 0.614; D(0) = 351 cGy). Paclitaxel caused a higher degree of clonogenic inhibition in HCT-116 (D(0) = 0.7 nM) than HT-29 (D(0) = 1.11 nM) cells (P < 0.06). When paclitaxel and radiation were combined, an enhanced radiosensitizing effect (P < 0.05) was observed in HCT-116 cells (SF(2) = 0.138; D(0) = 103 cGy), whereas in HT-29 cells no significant radiosensitization of paclitaxel was observed (SF(2) = 0.608; D(0) = 306 cGy). However, pretreatment with paclitaxel followed by multifractionated low dose radiation (0.5- or 1-Gy fractions for a total dose of 2 Gy) significantly enhanced the radiosensitizing effect in both HCT-116 and HT-29 cells.

CONCLUSIONS

The results of the current study suggested that multifractionated radiation given at very low doses after exposure of cells to paclitaxel conferred a potent radiation sensitizing effect irrespective of p53 status.

In vivo and in vitro comparison of the short-term hematopoietic toxicity between hydroxyurea and trimidox or didox, novel ribonucleotide reductase inhibitors with potential anti-HIV-1 activity

Inhibitors of the cellular enzyme ribonucleotide reductase (hydroxyurea, [HU]) have been proposed as a new therapeutic strategy for the treatment of HIV type-1 (HIV-1) infection. However, HU use may be limited by the frequent development of hematopoietic toxicity. We report here short-term hematopoietic toxicity in mice receiving HU when compared to either of two more potent enzyme inhibitors, didox (DX) and trimidox (TX). High dose HU, DX, and TX monotherapy (500, 460, and 220 mg/kg/day respectively) was administered by daily i.p. injection (Monday-Friday) to C57BL/6 mice for 10 weeks. Effects on hematopoiesis were established by quantitating peripheral blood indices (hematocrit, hemoglobin, mean corpuscular volume, mean cell hemoglobin, mean corpuscular hemoglobin concentration, RBC, and WBC) and numbers of colony-forming units-granulocyte-macrophage (CFU-GM) and BFU-E from bone marrow and spleen. HU produced rapid induction of a macrocytic hypochromic anemia and altered white blood cell kinetics associated with myelosuppression defined as reduced marrow organ cellularity and induction of splenic extramedullary hematopoiesis. Compared to HU, TX and DX induced fewer changes in peripheral blood indices and CFU-GM and BFU-E per hematopoietic organ. In vitro human and murine marrow CFU-GM and BFU-E colony formations were assayed in the presence of dose escalation HU, DX, or TX (0, 1, 10, 50, 100, and 200 microM). HU inhibited colony formation more than either DX or TX. These in vivo and in vitro studies suggest that novel ribonucleotide reductase inhibitors TX and DX may provide an effective alternative to HU in HIV-1 therapy because they demonstrate reduced hematopoietic toxicity.

Influence of lithium on the cellular environment

In order to study the influence of lithium on the cellular environment, we conducted research in multiple experimental models: groups of rats with normal cerebral excitability and groups susceptible to audiogenic convulsion, rat neuroglia cultures and perfusion of dog isolated head. We assumed blood composition to be a good indicator of cell environment composition. Blood serotonin level differs in the two groups of animals. Lithium induces a decrease of blood serotonin and an increase of amine concentration in some of the cerebral regions of rats susceptible to audiogenic convulsions. Inverse effects occur in rats with normal cerebral excitability. In the perfused, isolated head of a dog, lithium immediately decreases blood serotonin level. Na and water have a diminished metabolization during the first 24 hrs. in both animal groups. Decrease in metabolization is somewhat greater in hyperexcitable animals. Within 48 hrs. after lithium injection, there is an increase of Na metabolization, probably determined by its storage in the interstice. Renal elimination of K decreases under the influence of lithium 48 hrs. after administering one dose of lithium. Lithium induces, immediately after injection, a decrease of blood Na concentration in the efferent flow of the jugular vein of a perfused dog head. When used in cell cultures, lithium (2 mM concentration) stimulates glial cells division (astrocytes, oligodendrocytes), increases their growth and aging rates. The effects of lithium may be due to its toxicity. Therefore, lithium alters the composition of the cellular environment depending on dose and on the state of the body.

Use of an international faculty/student exchange program as a process to establish and improve graduate education and research within an allied health discipline

It has been recognized in the allied health professions that allied health disciplines must enhance and increase their research and scholarly activity. If faculty/staff are to be judged in the academic environment in which they work, their efforts to conduct research must be supported. Recognition for academic scholarship measured by the performance of research and scholarly activity is often difficult for faculty/staff to attain because of increased demands for scheduled time devoted to classroom instruction and student advising. This inability for faculty/staff to engage in research and scholarly activity often is enhanced by the lack of proper and adequate facilities and equipment. Also important is the role of graduate education, which itself, provides a stimulus for the performance of research and scholarly activity. This article reports outcomes achieved by an international faculty/staff-student program that provides an opportunity for faculty/staff and students within an allied health discipline to conduct research and scholarly activity. This program could serve as a model to identify the strengths and benefits that can be achieved by such programs. This program is capable of improving the research and scholarly activity of all academic units within an allied health discipline.

The effects of lithium in reversing hydroxyurea induced suppression of hematopoietic progenitor cells in vitro using retroviral infected long-term marrow cultures

Lithium has been known for its ability to induce the production of hematopoietic cells following administration in vivo to minimize the toxic effects on hematopoiesis as a consequence of drug treatment. The drug hydroxyurea (HU), a ribonucleotide reductase inhibitor, has been used in the treatment of a variety of neoplastic and non-neoplastic diseases, such as cancer and sickle cell anaemia. Hydroxyurea has more recently been implicated for use in the treatment of acquired immunodeficiency syndrome (AIDS). However, its major limitations have been due to its toxicity. Hydroxyurea selectively inhibits DNA synthesis and due to its brief duration, the drug is only toxic to those cells which are selectively synthesizing DNA during the period of exposure. The most important of these toxicities, and which serves as a dose limiting factor in treatment, is the induction of bone marrow suppression. In this study we investigated the possible beneficial effects of administering lithium (LiCl) to murine leukemia virus (MuLV) infected and non-infected long term bone marrow cultures (LTBMC). These cultures were then treated with either 0.2 mM hydroxyurea, 1.0 mM LiCl, or a combination of both. Samples were collected from LTBMC supernatants at 1, 2, 3, 4, 5 and 6 weeks post-treatment. Culture supernatants were then monitored to observe their repopulation of hematopoietic progenitors. The results demonstrated the effects of lithium in restoring hydroxyurea suppressed numbers of myeloid (CFU-GM) progenitors to within a normal range and also in re-establishing erythroid (BFU-E) progenitors.

The effects of lithium gamma-linolenic acid in reversing LPBM5 MuLV induced suppression of hematopoietic progenitor cells in vitro

Lithium gamma linolenic acid (Li-GLA), was evaluated for its possible role as an antiviral agent. Li-GLA 15 micrograms ml-1 was administered to both normal and LP-BM5 MuLV retroviral infected murine bone marrow cultures. After 2 weeks of treatment, numbers of progenitors being produced by infected/treated cultures were reduced to some 10% that of normal cultures. In the remaining 4 weeks, numbers of CFU-GM and BFU-E hematopoietic progenitors returned within normal range. The efficacy of Li-GLA in relieving retroviral hematopoietic bone marrow suppression correlates to a reduction in interleukin-4 (IL-4) secretion, normally elevated in association with LP-BMP5 infection. These data indicate that this reduction in bone marrow suppression of LP-BMP5 infected cells may be due to a killing of infected cells by the Li-GLA, rather than stimulating hematopoiesis as with other lithium compounds. To conclude this may indicate the possible dual effect of administration of LiGLA to virally infected individuals in reducing viral titre and to lower the toxicities associated with long term drug therapy.

Effective use of ribonucleotide reductase inhibitors (Didox and Trimidox) alone or in combination with didanosine (ddI) to suppress disease progression and increase survival in murine acquired immunodeficiency syndrome (MAIDS)

Ribonucleotide reductase inhibitors (RRIs) have been recently shown to inhibit retroviral replication. We examined a new series of RRIs, 3,4-dihydroxybenzohydroxamic acid (Didox) and 3,4,5-trihydroxybenzohydroxamidoxime (Trimidox) for their ability to alter disease progression in murine acquired immunodeficiency syndrome (MAIDS), both alone and in combination with 2',3'-dideoxyinosine (ddI). MAIDS disease was induced by inoculation of female C57BL/6 mice with the LP-BM5 murine leukemia virus (MuLV) and disease progression characterized by extensive peripheral lymphadenopathy and splenomegaly. Efficacy of treatment with these drugs was based upon their ability to influence survival and disease pathophysiology by monitoring the development of splenomegaly. Toxicity was determined by changes in body weight, total peripheral white blood cell count and hematocrit. Didox or trimidox monotherapy was associated with increased survival and decreased disease pathophysiology, with no apparent toxicity. Combined with ddI, their ability to reduce development of viral induced splenomegaly was enhanced compared to trimidox, didox or ddI alone. These results demonstrate RRIs have potent activity in reversing the disease manifestations characteristic of MAIDS. Further studies are warranted to determine human clinical efficacy.

The regulation of phospholipase-A2 (PLA-2) by cytokines expressing hematopoietic growth-stimulating properties

Various growth factors released by macrophages and other cell types modulate normal hematopoiesis. The physiological mechanisms whereby these molecules interact with specific target cells are ill defined. Eicosanoids, the products of fatty acid metabolism, are known to regulate cell proliferation and differentiation. The release of membrane-bound phospholipid by phospholipase-A2 (PLA-2) is the first critical step in the initiation of membrane remodeling and eventually eicosanoid synthesis. We report here data that demonstrates how various cytokines exhibit a marked hydrolytic activity mediated through PLA-2 against both [1-14C] oleic acid- and [1-14C] arachidonic acid-labeled Escherichia coli (micelle) substrates. PLA-2 extracts were prepared from neutrophils elicited by injecting rats ip with 8% glycogen. The rate of hydrolysis of free fatty acids from the phospholipid substrate was found to be linear, rapid, and pH dependent and was calculated to be 30 nmoles of phospholipid/hr/mg protein lysate. Cytokines (i.e., interleukin-1 [IL-1, human and murine recombinant, alpha], mouse lung cell-derived colony-stimulating factor [L-CSF], granulocyte-macrophage colony-stimulating factor [murine recombinant GM-CSF], tumor necrosis factor [murine recombinant TNF-alpha], and granulocyte colony-stimulating factor [human recombinant, G-CSF] all induced PLA-2 activity with the release of free fatty acids above basal levels. In contrast, lipopolysaccharide (LPS), interleukin-2, (IL-2, human recombinant), and macrophage colony-stimulating factor (M-CSF) did not significantly activate PLA-2 hydrolysis. The activation of this membrane-bound enzyme-substrate complex by these growth factors may serve as a mechanism whereby the appropriate target cells expressing receptors respond through either direct or secondary signals leading to the formation of free fatty acids with the eventual synthesis of prostanoid or lipoxygenase products, resulting in cellular proliferation and differentiation.

Suppression of hematopoietic support function is associated with overexpression of interleukin-4 and transforming growth factor-beta 1 in LP-BM5 murine-leukemia-virus-infected stromal cell lines

Murine acquired immunodeficiency syndrome (MAIDS) induced by defective LP-BM5 murine leukemia virus (MuLV) is a disease with many similarities to human AIDS. Our previous studies demonstrated that the depressed hematopoiesis observed in LP-BM5-infected marrow cultures could be attributed to a defective hematopoietic stroma. We report now the generation of permanent stroma cell lines from noninfected and LP-BM5-infected marrow cultures. Retrovirus infection was confirmed by the polymerase chain reaction for detecting viral genome expression of the p12 envelope glycoprotein. The ability of these cell lines to support in vitro hematopoiesis was evaluated. The results demonstrated that when cocultured with normal or infected nonadherent mononuclear cells, noninfected cell lines efficiently supported the production of hematopoietic progenitors, whereas in virus-infected progenitors was suppressed. Expression of cytokine genes in stromal cell lines was also examined. All cell lines expressed equivalent levels of transcripts for interleukin (IL)-1 beta, IL-2, IL-3, IL-6, IL-7, IL-10, interferon, tumor necrosis factor-alpha and stem cell factor. However, infection was associated with higher expression of IL-4 and transforming growth factor-beta 1. These findings demonstrate that infected stomal cell lines generate a defective hematopoietic microenvironment to produce altered cytokine expression and faulty hematopoiesis. Further characterization of these defective cell lines should assist elucidation of the mechanism(s) whereby retroviruses alter hematopoiesis ultimately leading to the generation of immunodeficiency.

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.

Increased hematopoietic toxicity following administration of interferon-a with combination dideoxynucleoside therapy (zidovudine plus ddI) administered in normal mice

Because of the urgency to develop drugs which will effectively combat HIV infection, many combination therapies which have proved effective against HIV in vitro have undergone, or are undergoing clinical trial. Unfortunately many of drugs are being used without rigorous and exhaustive preclinical evaluation to assess their potential to develop hematopoietic toxicity. We report here the results of two in vivo studies performed to analyze the effect of combined zidovudine (AZT) plus didanosine (ddI) therapy, either with or without interferon-a (IFN-a), on murine hematopoiesis. Normal C57BL/6 female mice were administered AZT (1.0 mg/ml) plus dose-escalation ddI (0.1, 1.0 and 2.5 mg/ml) placed in their drinking water. Control mice received IFN-å (100 units/ml) alone. Mice were serially bled and sacrificed over a six-week period for assessment of hematopoietic toxicity measured by peripheral blood indices and assays of hematopoietic progenitors, i.e., erythroid (BFU-E), myeloid (CFU-GM), and megakaryocyte (CFU-Meg) cultured from bone marrow and spleen. AZT plus dose-escalation ddI decreased the hematocrit and white blood cell count when administered to normal mice compared to untreated controls during the six-week examination period. Marrow derived BFU-E, CFU-GM, and CFU-Meg were all reduced, however an increase was observed from the spleen for all three progenitor cell types. Use of IFN-a, in addition to combination AZT plus ddI further decreased the hematocrit, white blood cells and platelets. Marrow derived CFU-GM and CFU-Meg were increased slightly and only marginally for BFU-E with a similar response observed from the spleen. These results demonstrate that combination AZT plus ddI when used in vivo may produce synergistic hematopoietic toxicity, and that the addition of IFN-a to this treatment regimen increases this toxicity. These data indicate caution when this therapeutic approach is suggested for patients infected with HIV. If used, these patients will require careful monitoring for blood cell toxicity.

Stromal cell lines derived from LP-BM5 murine leukemia virus-infected long-term bone marrow cultures impair hematopoiesis in vitro

Murine acquired immunodeficiency syndrome (MAIDS) induced by defective LP-BM5 murine leukemia virus is a disease with many similarities to human AIDS. Previous studies indicated that the depressed hematopoiesis observed in LP-BM5-infected marrow cultures may be attributable to a defect of hematopoietic stroma. We report here the generation of permanent stromal cell lines from noninfected and LP-BM5-infected marrow cultures. Retrovirus infection was confirmed by polymerase chain reaction for viral genome. The ability of these cell lines to support in vitro hematopoiesis was studied. Results indicated that, when cocultured with normal or infected nonadherent mononuclear cells, noninfected cell lines efficiently supported the production of hematopoietic precursors, whereas viral-infected cell lines induced suppression of both normal and viral-infected progenitors. Expression of cytokine genes in stromal cell lines was also examined. All cell lines expressed equivalent levels of transcripts for stem cell factor and tumor necrosis factor alpha. However, infection was associated with higher levels of interleukin-4 and transforming growth factor beta 1 transcript expression. These findings suggest that infected stromal cell lines exhibit a defective hematopoietic microenvironment that produced altered cytokine expression resulting in faulty hematopoiesis. Further characterization of the defective cell lines should prove valuable for studies of the pathogenesis of murine AIDS.

Prevention of hematopoietic myeloid and megakaryocyte toxicity associated with zidovudine in vivo in mice with recombinant GM-CSF

We studied the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the suppression of hematopoiesis associated with the use of the antiviral drug zidovudine (AZT) administered in vivo to normal mice, as determined by measuring peripheral blood indices, and assays of hematopoietic progenitors, i.e. erythroid (CFU-E/BFU-E), myeloid (CFU-GM), and megakaryocyte (CFU-Meg) from bone marrow and spleen. Previous studies from this laboratory have established that dose-escalation zidovudine induced a dose-dependent decrease in hematocrit, WBC, and platelets with altered populations of bone marrow and splenic erythroid, myeloid and megakaryocyte progenitors when administered to normal mice. Daily administration of GM-CSF (10 micrograms/kg/bw) was associated with altered peripheral blood indices and progenitor cells. Dose-escalation AZT, i.e. 0.1, 1.0 and 2.5 mg/ml, was associated with a comparable reduction in all indices, i.e. hematocrit, WBC, and platelets during the 6-week examination period. GM-CSF reduced zidovudine-induced myeloid toxicity (concentration < 2.5 mg/ml) which was associated with an increase in bone marrow and splenic CFU-GM. High concentration, i.e. 2.5 mg/ml still produced myelosuppression irreversible with GM-CSF. GM-CSF induced a reduction in circulating platelets following zidovudine treatment at weeks 2 and 4 with the 1.0 mg/ml and 2.5 mg/ml treatment groups respectively, compared to a persistent decrease in platelets in the presence of zidovudine alone. GM-CSF BFU-E were elevated indicating the restriction in erythoid differentiation was still present. These studies demonstrate GM-CSF influences myeloid and megakaryocyte recovery, but not the erythoid suppression associated with the antiviral drug zidovudine.

Influence of interleukin-3 (IL-3) on the hematopoietic toxicity associated with combination anti-viral drugs (zidovudine and DDI) in vitro using retrovirus-infected bone marrow cells

The drug zidovudine (AZT), a synthetic thymidine analog, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has been associated with the development of hematopoietic toxicity manifested by anemia, neutropenia, and on occasion thrombocytopenia. This toxicity has resulted in the development of alternative dideoxynucleoside drugs capable of exerting anti-viral potency while minimizing the risk for inducing organ toxicities. One such dideoxynucleoside drug is 2',3'-dideoxyinosine (ddI). Clinical trials are currently evaluating the effect of combination anti-viral drug treatment such as zidovudine plus ddI. We report here the results of studies designed to evaluate the effect of interleukin-3 (IL-3) on its ability to influence the hematopoietic toxicity associated with zidovudine and ddI following combination with retroviral-infected murine bone marrow cells. Toxicity was evaluated by quantitating several classes of hematopoietic progenitor stem cells such as granulocyte-macrophage (CFU-GM), erythroid (CFU-E and BFU-E) and megakaryocyte (CFU-Meg). Dose-escalation IL-3 provided protection of anti-viral drug induced suppression of progenitor cells when combined in the presence of the ID50 concentration of either zidovudine or ddI; however, when zidovudine and ddI were combined, IL-3 was less effective in providing protection against drug-induced toxicity at any concentration examined. These results indicate that IL-3 is effective in reducing anti-viral drug-induced hematopoietic toxicity associated with single-agent use; however, IL-3 is less effective when such drugs are used in combination.

Effect of combination interleukin-1 and erythropoietin in ameliorating the hematopoietic toxicity associated with the use of zidovudine administered to normal mice

Use of the anti-viral drug zidovudine in the treatment of acquired immunodeficiency syndrome (AIDS) has been associated with the development of hematopoietic toxicity. Several hematopoietic growth factors have been investigated in their ability to modulate such toxicity; however, no single factor has been demonstrated to produce restoration of hematopoiesis following use with zidovudine. We report results describing the effect of combination interleukin-1 (IL-1) and erythropoietin (Epo) in their ability to modulate the hematopoietic toxicity associated with dose-escalation zidovudine administered in normal mice. When administered over a six-week period, IL-1 and Epo raised the packed red cell volume, white blood cell and platelet counts in control mice and mice receiving dose-escalation zidovudine. These effects were attributed in part to the ability of combination IL-1 and Epo to increase erythroid, myeloid and megakaryocyte progenitor stem cells from bone marrow and spleen. These results indicate that use of combined IL-1 and Epo may be efficacious in ameliorating the hematopoietic toxicity associated with the use of zidovudine.

Sustained zidovudine treatment on hematopoiesis in immunodeficient mice

Zidovudine (AZT) has been the drug of choice in the treatment of human AIDS; however, associated with the use of zidovudine has been the development of hematopoietic toxicity, the mechanism of which is not clearly defined. We report here studies designed to evaluate dose-escalation of zidovudine, i.e. 0.1 and 1.0 mg/ml placed in the drinking water on hematopoiesis in C57BL/6 normal and LP-BM5 immunodeficiency virus-infected mice. Over a 6-week evaluation period, compared to normal, non-virus-infected controls, murine immunodeficiency (MAIDS) infection was associated with reduced hematopoietic progenitors, i.e. CFU-E, BFU-E, CFU-GM, and CFU-Meg from bone marrow and spleen. Following zidovudine treatment, further suppression of marrow-derived progenitors was observed, while increased numbers of progenitors were obtained from the spleen. Spleen-derived erythroid progenitors, i.e. CFU-E, were increased by 950% (P < 0.001) from MAIDS-infected animals receiving 1.0 mg/ml of drug following 4-weeks exposure compared to non-drug-treated MAIDS control animals. Splenic BFU-E were increased 654% following 6-weeks exposure compared to non-drug-treated MAIDS-infected mice. This study suggests that the bone marrow is particularly sensitive to zidovudine toxicity which, at least early in exposure, appears to be compensated by splenic-derived hematopoiesis, in particular, erythropoiesis. Overt toxicity develops when, at least in this immunodeficiency model, the spleen is unable to provide progenitors in response to continued zidovudine exposure in vivo.

Lithium and anti-viral drug toxicity: II. Further studies on the ability of lithium to modulate the hematopoietic toxicity associated with the anti-viral drug zidovudine (AZT)

Lithium is an agent capable of influencing many aspects of blood cell production, in particular, the formation of granulocytes. Because of this property, lithium has been demonstrated to be an effective agent whenever granulocyte production is either faulty or inadequate. The anti-viral drug zidovudine (AZT) has used been extensively in the treatment of acquired immune deficiency syndrome (AIDS). However, its effectiveness is limited because of the myelosuppression and bone marrow toxicity associated with its use. We have previously demonstrated that lithium, when combined with AZT in vitro with normal bone marrow cells or when administered in vivo to mice receiving dose-escalation AZT, reduced the myelosuppression and marrow toxicity of AZT significantly. We report here further studies designed to evaluate the extent of lithium's capacity to modulate AZT toxicity by investigating the ability of lithium to influence blood cell production when administered to normal mice during an initial exposure to AZT. C57BL6 were administered dose-escalation AZT (1.0 mg/ml and 2.5 mg/ml) for a period of 4-weeks in the presence or absence of lithium carbonate (1 mM). This was followed by an additional 4-week period during which mice received only AZT. Animals were analyzed on a weekly basis for their peripheral blood indices. Animals receiving dose-escalation AZT demonstrated anemia, thrombocytopenia, and neutropenia which was dose-related. During the period when animals received combination lithium/AZT, there was significantly less anemia, thrombocytopenia, and neutropenia as compared to the AZT controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure to establish long-term marrow cultures from immunodeficient mice (MAIDS): effect of zidovudine in vitro

We report here the results of studies examining the ability of zidovudine (AZT) to influence the establishment and maintenance of long-term marrow cultures (LTMC) using marrow from murine immunodeficient mice (MAIDS). Normal C57BL6 mice were infected with LP-BM5 (MuLV) immunodeficiency virus (10 micrograms total protein) intraperitoneally. Five weeks after viral infection, mice were sacrificed and marrow was harvested from normal non-virus-infected and virus-infected animals. LTMC were established in the presence or absence of dose escalation of AZT, that is, 10(-6), 5 x 10(-7), and 10(-7) M in vitro. Compared with controls prepared from normal bone marrow, LTMC using MAIDS-infected marrow failed to establish and subsequently release supernatant-derived mononuclear cells. The addition of AZT was ineffective in either establishing LTMC or consistently producing mononuclear cells. Measurements of erythroid (BFU-E), myeloid (CFU-GM), and megakaryocyte (CFU-Meg) precursors were all depressed and none were observed after 5 weeks of culture. Treatment with AZT failed to reverse this depression of stem cell progenitors. Microscopic examination of cultures at 10 weeks demonstrated a failure of MAIDS-LTMC to establish an adequate stromal layer compared to LTMC prepared form non-virus-infected controls. This data indicate that LP-BM5 MuLV infection alters the establishment of a normal functioning hematopoietic microenvironment or stroma. Acknowledging that important differences between MAIDS and human AIDS exist, the implications of these findings concerning the establishment of the immunodeficiency disease state in human immunodeficiency virus infection is discussed.

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

The drug zidovudine (AZT), a synthetic thymidine analogue, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has induced haematopoietic toxicity manifested by anaemia, neutropenia, and overall bone marrow suppression. The monovalent cation lithium has been shown to be an effective agent capable of modulating several aspects of haematopoiesis such as the induction of neutrophilia, thrombopoiesis, and protection against suppression of hematopoietic progenitor stem cells following exposure to anti-cancer drugs and/or radiation at doses commonly used in the treatment of malignant disease. We report here the result of studies designed to evaluate the effectiveness of lithium in reversing zidovudine-induced haematopoietic suppression when administered to normal mice in vivo in the presence of dose-escalation zidovudine. Lithium carbonate (Li2CO3) reversed zidovudine toxicity as measured by increases in peripheral WBC, platelets, and CFU-GM and CFU-Meg haematopoietic progenitors; however lithium was insufficient in reversing the reduction of erythropoiesis associated with zidovudine use in vivo. These results further confirm the effective use of lithium to reverse the development of myelosuppression and thrombocytopenia associated with the anti-viral drug zidovudine, but is less effective in ameliorating the induction of anaemia.

Comparison of dideoxynucleoside drugs (DDI and zidovudine) and induction of hematopoietic toxicity using normal human bone marrow cells in vitro

The drug zidovudine (AZT), a synthetic thymidine analog, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has induced hematopoietic toxicity manifested by anemia, neutropenia and on occasion thrombocytopenia. Such toxicity has stimulated the development of alternative dideoxynucleoside drugs capable of exerting anti-viral potency while minimizing the risk for inducing organ toxicities. One such alternative dideoxynucleoside drug is 2',3'-dideoxyinosine (ddI). Recent therapeutic anti-viral strategy, now undergoing clinical trial, is the evaluation of combined zidovudine ddI treatment. Unfortunately a complete assessment of their potential toxicity using this drug regimen has not been thoroughly examined. We report here the results of studies comparing the toxicity profile of zidovudine versus ddI on their ability to influence several classes of hematopoietic progenitor stem cells, e.g. granulocyte--macrophage (CFU-GM), megakaryocyte (CFU-Meg) and erythroid (CFU-E/BFU-E) following in vitro co-culture with normal human bone marrow. Since the main clinical toxicity associated with zidovudine in vivo is the development of anemia, additional in vitro studies compared the dose-escalation effect of erythropoietin in the presence of combined zidovudine and ddI. CFU-GM, CFU-Meg, CFU-E and BFU-E were all reduced (P < 0.05) following incubation with either zidovudine or ddI thus determining their ID50 concentrations for these classes of hematopoietic progenitors; however, the extent of toxicity associated with ddI was lower than what was observed with zidovudine. More importantly, dose-escalation of erythropoietin was effective in reversing the inhibition observed for ddI on erythroid progenitors CFU-E and BFU-E (P < 0.05), an effect not reported with zidovudine in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of the hematopoietic toxicity associated with zidovudine in vivo with IL-1 alone or in combination with GM-CSF administered to normal mice

We studied the effect of interleukin-1 (IL-1 alpha) either alone or administered with GM-CSF on the induction of hematopoietic toxicity associated with zidovudine (AZT) in vivo, as determined by peripheral blood indices, and assays of hematopoietic progenitors, i.e., erythroid (BFU-E), myeloid (CFU-GM), and megakaryocyte (CFU-Meg) cultured from bone marrow and spleen. Previous results reported from this laboratory have established dose-escalation of zidovudine to normal mice induced a dose-dependent decrease in hematocrit, WBC, and platelets with altered populations of marrow and splenic erythroid, myeloid and megakaryocyte progenitors. Daily administration of IL-1 alpha (recombinant murine, 5 u/animal) with or without GM-CSF (recombinant murine (10 micrograms/kg/bw) was associated with reduced AZT-toxicity as measured by increases in peripheral blood indices and progenitor stem cells, i.e., CFU-GM, CFU-Meg and BFU-E cultured from either bone marrow and spleen. The presence of GM-CSF amplified the effect observed with IL-1 especially with respect to myelopoiesis. These results demonstrate IL-1 with or without GM-CSF reverses AZT-hematopoietic toxicity when used in vivo.

Effect of lithium in murine immunodeficiency virus infected animals

Murine AIDS (MAIDS) is a disease that shows many similarities to human HIV infection. The etiological agent of MAIDS is a defective murine leukemia virus that seems to be able to induce disease in the absence of viral replication. This animal model has been useful in stimulating the search of answers to questions and the formation of new hypotheses related to human AIDS. The monovalent cation lithium can influence a number of immunohematopoietic cell types and cellular processes where proliferation and differentiation occur. We describe here the result of in vivo studies investigating the effect of lithium treatment on MAIDS-infected mice. Viral control and lithium-treated animals were monitored for survival and development of MAIDS pathology. MAIDS animals treated with lithium demonstrated a marked reduction in their development of lymphadenopathy and splenomegaly. Both MAIDS control and lithium-treated virus-infected mice developed evidence of lymphoma; however, the involvement was much more massive both at the gross and microscopic levels in the MAIDS control compared with the lithium-treated mice. These data suggest that lithium may be effective in modulating murine immunodeficiency virus infection and raise important questions related to the potential role lithium may play in the pathophysiological processes associated with retroviral infections.

In-vivo effect of interleukin 3 and erythropoietin, either alone or in combination, on the hematopoietic toxicity associated with zidovudine

We studied the effect of erythropoietin (EPO) and interleukin 3 (IL-3), either alone or in combination, on the hematopoietic toxicity associated with zidovudine in vivo, as determined by peripheral blood indices, and assay of hematopoietic progenitors, i.e. erythroid (CFU-E/BFU-E), myeloid (CFU-GM) and megakaryocyte (CFU-Meg) from bone marrow and spleen. Previous studies from this laboratory have established that dose escalation of zidovudine to normal mice induced a dose-dependent decrease in hematocrit, white blood cells and platelets with altered populations of marrow and splenic erythroid, myeloid and megakaryocyte progenitors. Daily administration of EPO (50 U/animal, i.p.) and/or IL-3 (5 U/animal, i.p.) was associated with altered peripheral blood indices and progenitor cells. In general, use of EPO and IL-3 alone reduced zidovudine-induced toxicity, notably in erythropoiesis; however, combination EPO/IL-3 was associated with enhanced toxicity with an observed rebound only with the use of < 2.5 mg/ml drug; 2.5 mg/ml drug in the presence of combination EPO/IL-3 accelerated zidovudine-erythroid toxicity. A similar response was noted with circulating platelets and megakaryocyte progenitors. Use of EPO or IL-3, either alone or in combination, failed to reverse zidovudine-induced neutropenia. These studies demonstrate that use of EPO or IL-3, either alone or in combination may serve as an effective adjuvant therapy to modulate the erythroid toxicity associated with lower doses of zidovudine; however, this cytokine therapy was ineffective modulating zidovudine-induced myelosuppression when used in vivo. A reversal in zidovudine-induced myeloid toxicity, therefore may require the use of a myelopoiesis inducing cytokine.

Proliferation of abnormal bone marrow histiocytes, an undesired effect of granulocyte macrophage-colony-stimulating factor therapy in a patient with Hurler's syndrome undergoing bone marrow transplantation

Granulocyte macrophage-colony-stimulating factor (GM-CSF) has shown promise as a means of alleviating leukopenia associated with a wide variety of disorders. It is currently undergoing evaluation as an adjunct to bone marrow transplantation but its use in patients with metabolic disorders, such as Hurler's syndrome (HS), has not been explored. We followed bone marrow morphology in a 2-year-old male with HS who received up to 8 micrograms/kg GM-CSF per day because of failure of allogeneic bone marrow engraftment. Both premortem and postmortem bone marrow sampling revealed almost complete replacement of the marrow space by sheets of histiocytes demonstrating metachromatic cytoplasmic granules. Such cells were present in far greater numbers than are usually seen in untreated patients with HS or patients with HS undergoing successful bone marrow transplantation without GM-CSF. Moreover, the in vitro culture of bone marrow from a second HS patient showed a GM-CSF dose-related increase in colony formation up to a dose of 250 units/ml. Microscopic examination of these colonies showed a high percentage of histiocytes identical to those seen in the patient's bone marrow. These observations suggest that caution should be exercised when considering administration of CSFs to patients with HS and similar metabolic storage diseases.

In vitro modulation of the toxicity associated with the use of zidovudine on normal murine, human, and murine retrovirus-infected hematopoietic progenitor stem cells with basic fibroblast growth factor and synergistic activity with interleukin-1

The antiviral drug used in the treatment of acquired immunodeficiency syndrome, zidovudine, has proved effective in ameliorating the morbidity and mortality associated with human immunodeficiency virus infection. However, associated with zidovudine is the development of severe bone marrow toxicity manifested by anemia, neutropenia, and occasionally thrombocytopenia. We report the results of studies that demonstrate the ability of basic fibroblast growth factor (B-FGF) to reduce zidovudine toxicity to several classes of hematopoietic progenitors (granulocyte-macrophage, CFU-GM; megakaryocyte. CFU-Meg; and erythroid, BFU-E) from normal murine, human, and murine retrovirus-infected bone marrow cells when cocultured with zidovudine in vitro. Optimal response to B-FGF was observed at a dose concentration of 10 ng/ml. The specificity of B-FGF was demonstrated in the presence of protamine sulfate, an effective inhibitor of B-FGF mitogenic activity. In addition, synergistic activity of B-FGF on zidovudine-induced hematopoietic stem cell toxicity was observed in the presence of interleukin 1 (IL-1) (30 ng/ml). These studies demonstrate that B-FGF is capable of reducing the hematopoietic toxicity associated with zidovudine and that such an effect can be amplified in the presence of IL-1.

Suppression of murine hematopoiesis in vivo after chronic administration of zidovudine: evidence that zidovudine-induced anemia is the result of decreased bone marrow-derived, erythropoietin-responsive progenitor cells

We studied the long-term effect of continued zidovudine exposure in mice on hematopoiesis, as determined by peripheral blood indices, assays of erythroid (colony-forming unit-erythroid [CFU-E] and burst-forming unit-erythroid [BFU-E]), myeloid (CFU-granulocyte-macrophage [GM]), megakaryocyte (CFU-Meg), and plasma titers of erythropoietin, granulocyte-macrophage colony-stimulating factor, megakaryocyte colony-stimulating factor, and tumor necrosis factor-alpha. Dose-escalation of zidovudine (0.1, 1.0, and 2.5 mg/ml) induced a dose-dependent decrease in hematocrit, white blood cells, and platelets. High-dose drug, i.e., greater than 1.0 mg/ml, reduced marrow CFU-E; splenic CFU-E was increased after 1 week, then declined. BFU-E was increased at Weeks 1 and 2, then declined to control levels. Splenic BFU-E rose during the examination period that was dose-dependent. Femoral CFU-GM was cyclic, i.e., low-dose drug, 0.1 mg/ml, was increased gradually, the declined; higher doses of 1.0 and 2.5 mg/ml were lower until Week 5, then were above controls. Splenic CFU-GM was increased initially at Week 2 (1.0 mg/ml), then declined; the higher dose (2.5 mg/ml) increased initially, then declined below controls (Week 6). Femoral CFU-Meg was increased after low-dose drug and inhibited after high dose (2.5 mg/ml). Splenic CFU-Meg was reduced initially, followed by an increase at Week 4. Plasma titer of erythropoietin was elevated, proportional to dose escalation of drug, and inversely proportional to the hematocrit. No difference was observed in plasma levels of granulocyte-macrophage colony-stimulating factor, megakaryocyte colony-stimulating factor, or tumor necrosis factor-alpha. This study demonstrates that zidovudine-induced anemia results from: (i) inadequate numbers of bone marrow-derived, erythropoietin-dependent hematopoietic progenitors, i.e., CFU-E; and (ii) a shift in erythropoietin-responsive progenitors from bone marrow to spleen capable of responding to obligatory growth factors.

Effective modulation of the haematopoietic toxicity associated with zidovudine exposure to murine and human haematopoietic progenitor stem cells in vitro with lithium chloride

The drug zidovudine (AZT), a synthetic thymidine analogue, has been used in the treatment of acquired immunodeficiency syndrome (AIDS). Clinical use of zidovudine has induced haematopoietic toxicity manifested by anaemia, neutropenia, frequent thrombocytopenia, and overall bone-marrow suppression. The monovalent cation lithium has been shown to be an effective agent capable of modulating several aspects of haematopoiesis such as the induction of neutrophilia, thrombopoiesis, and protection against suppression of haematopoietic progenitor stem cells following exposure to anticancer drugs and/or radiation in the treatment of malignant disease. We here report the results of studies designed to evaluate the effectiveness of lithium in reversing and/or protecting against either murine or human bone marrow derived haematopoietic progenitors, i.e. (CFU-GM, CFU-Meg, and BFU-E) when co-cultured in the presence of zidovudine in vitro. Lithium chloride (LiCl) reversed zidovudine toxicity to either murine or human derived CFU-GM and CFU-Meg that was optimal at a concentration of 1 mM (P less than 0.05). However, the addition of lithium failed to influence zidovudine toxicity toward either murine or human BFU-E. In summary, these results support the scant clinical studies that have described the presence of neutrophilia and/or thrombopoiesis in zidovudine-treated AIDS patients receiving lithium. In addition, these data further confirm the need for more detailed evaluation of lithium as an adjuvant agent to reduce the haematopoietic toxicity associated with the use of antiviral therapy in HIV-infected patients.