Hemopoietic growth factors: a review

Changes in bone marrow-derived myeloid cells from thermally injured rats reflect changes in the progenitor cell population

Bone marrow progenitor cells develop into mature tissue myeloid cells under the influence of colony-stimulating factors. Cytokines that are elevated post-thermal injury have been shown to influence this process. We hypothesize that thermal injury alters myelopoiesis at the level of the progenitor cell. These differences should be visible after in vitro cultures that include colony-stimulating factors. Prior to culture, bone marrow at postburn day 1 (PBD1) was assessed for cell surface markers and the levels of myeloid progenitors. After culture in granulocyte/macrophage-stimulating colony-stimulating factor, the cell surface markers of the cultured cells were determined. PBD1 marrow from thermally injured rats had more progenitor cells responsive to granulocyte/macrophage-stimulating colony-stimulating factor than did sham. Cultured PBD1 marrow produced more CD90(br) MY(br) CD45(dim) CD4(-) MHCII(-) CD11b(dim) eosinophils than did sham. Cultured bone marrow from thermally injured animals produces myeloid cells with an altered phenotype. Similar changes in myelopoiesis may take place in vivo.

Pituitary-adrenocortical responses to the chronic administration of granulocyte colony-stimulating factor in rats

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor, but it may play a role in the regulation of the neuroendocrine system activity. Only few data are available about its possible influence on the pituitary gland. We have recently reported an acute stimulatory effect of G-CSF (and of GM-CSF) on adrenocorticotropic hormone (ACTH) secretion in rats in vivo. The purpose of the present study was to evaluate whether chronic administration of G-CSF affects ACTH and corticosterone secretion and growth processes of the rat anterior pituitary gland and adrenal cortex in vivo. We have demonstrated that G-CSF (at a dose of 10.0 microg/kg body weight (BW)) injected s.c. once daily (for 7 days), stimulated both ACTH and corticosterone secretion. Simultaneously, G-CSF treatment did not change the total anterior pituitary cell proliferation as revealed by immunohistochemical staining of proliferating cell nuclear antigen (PCNA). On the other hand, proliferative activity of corticotrophs, detected in the sections of the anterior pituitary using double-labeling. was significantly increased after treatment with G-CSF. Moreover, this growth factor induced an increase in the proliferation ratio in the entire adrenal equatorial section. These findings suggest an involvement of G-CSF in the regulation of pituitary-adrenal axis and support the hypothesis of bidirectional associations between the immune system and the endocrine glands.

Phase I trial of etoposide, carboplatin, and GM-CSF in extensive small-cell lung cancer: a Cancer and Leukemia Group B study (CALGB 8832)

The maximum tolerated dose (MTD) of etoposide and carboplatin without growth factor support was previously defined by Cancer and Leukemia Group B (CALGB) as 200 and 125 mg/m2/day x 3, respectively, given every 28 days to previously untreated patients who have extensive, small-cell lung cancer (SCLC). Myelosuppression was dose-limiting. The purpose of this phase I trial was to determine if granulocyte macrophage colony-stimulating factor (GM-CSF) support allows the dosage of the combination of etoposide and carboplatin to be increased above the previously determined MTD. In this CALGB study of 44 evaluable patients with performance status 0-2, cohorts were treated with etoposide and carboplatin given intravenously on days 1-3 followed by GM-CSF (molgramostim) given subcutaneously on days 4-18. Four dose levels of bacteria-derived recombinant GM-CSF (5, 10, 20 microg/kg/day and 5 microg/kg every 12 h), three dose levels of etoposide (200, 250, and 300 mg/m2/day x 3), and two dose levels of carboplatin (125 and 150 mg/m2/day x 3) were evaluated. There was no chemotherapy dose escalation in individual patients. With 5 microg/kg/d GM-CSF, the first etoposide and carboplatin cycle of 300 and 150 mg/m2/day x 3, respectively, could be administered with acceptable toxicity. However, GM-CSF did not allow repeated administration of this dose-escalated regimen every 21 days, since delayed platelet and/or neutrophil recovery was dose limiting in later cycles. These results demonstrate that GM-CSF alone has limited capability to support the repeated administration of high doses of etoposide and carboplatin. CALGB currently is testing the ability of interleukin (IL)-6 given with GM-CSF to ameliorate the cumulative myelosuppression of this intense regimen.

Ultrastructural changes of stromal cells of bone marrow and liver after cyclophosphamide treatment in mice

The direct effect of cyclophosphamide (CY) on bone marrow and liver stromal cells of DBA/2 and C57BL/6 mice after a single intraperitoneal dose of 300 mg/kg, was assessed. Ultrastructural observations were carried out 2,4,6,12,18, and 24 h and 2,3,5,7,10,15,22 and 30 days after CY in femoral bone marrow and liver fixed by immersion or vascular perfusion. A massive depletion of hemopoietic cells was observed in bone marrow as early as 12 h after CY treatment, and normality was recovered only after 10 days. Among stromal cells, sinus endothelial cells, reticular cells, and macrophages were particularly sensitive to CY and showed severe damage as soon as 2 h after treatment. There was also an important dilatation of sinusoids, and the presence of mature red cells in the hemopoietic parenchyma, and macrophages and immature cells in the lumen and in circulating blood demonstrated the loss of integrity of the endothelium. In the liver, injured cells showing vesiculation and disruption of endothelial and Kupffer cells of sinusoids were evident 6 h after CY. The alterations caused by CY were transient. Although recovery of the hemopoietic cells in bone marrow and liver was achieved by day 10, the stromal cells showed damage even 15 days after CY, and a return to normality was only reached on day 30. Thus, the effect of CY on stromal cells, that was longer lasting than the effect on the hemopoietic compartment, demonstrated a higher recovery capacity of hemopoiesis with respect to stromal cells. These results demonstrate that recovery of hemopoiesis occurred even while the severe damage inflicted by CY to the stromal cells remained unrepaired.

Constitutive production of multiple cytokines and a human chorionic gonadotrophin beta-subunit by a human bladder cancer cell line (KU-19-19): possible demonstration of totipotential differentiation

Bladder cancer cells have been shown to secrete a variety of factors that are not related to cells of urothelial origin. The histogenesis of these tumour developments is uncertain, and a variety of theories have been previously reported. In the present manuscript, we identify the factors constitutively produced by a human bladder cancer cell line (KU-19-19) that was found to produce beta human chorionic gonadotrophin (beta-hCG), granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 1alpha (IL-1alpha), interleukin 6 (IL-6) and interleukin 8 (IL-8). The cells were obtained from a case of metastatic carcinoma that was originally diagnosed to be a grade 3 (WHO classification), invasive transitional cell carcinoma of the bladder. On microscopic observation, the cultured cells exhibited an epithelial appearance with vacuole formation in their cytoplasm. Ultrastructural observations revealed relatively marked microvilli and a tight junction. Significant amounts of beta-hCG, G-CSF, GM-CSF, IL-1alpha, IL-6 and IL-8 concentrations in the supernatant from cultured cells were demonstrated by enzyme-linked immunosorbent assays, while the expression of mRNA of these marker proteins in cancer cells was also significantly exhibited by reverse transcription polymerase chain reaction (RT-PCR). In addition, the expression of G-CSF receptor and IL-6 receptor mRNA was also shown by RT-PCR. Xenograft transplantability using nude mice was observed in association with the presence of severe neutrophilia in the peripheral blood. These results indicate that this cell line appears to be an effective model for the study of transitional cell carcinoma of the bladder with multipotent differentiation potentials.

Designer cytokines: targeting actions to cells of choice

Some growth factors are therapeutically useful partly because restricted expression of their receptors limits their action to particular cell types. However, no unique stimulatory factor is known for many clinically relevant cell types, such as CD34+ hematopoietic stem cells. Here, soluble alpha receptor (R alpha) components for interleukin-6 (IL-6) and ciliary neurotrophic factor (CNTF) were targeted in an active form to cells expressing surface markers such as CD34 or CD45, thereby rendering those cells responsive to IL-6 or CNTF. The targeting of R alpha components may provide the means to create "designer" cytokines that activate a desired cell type expressing a specific cell surface marker.

Hepatic nitric oxide production following acute endotoxemia in rats is mediated by increased inducible nitric oxide synthase gene expression

In the present studies, we analyzed the effects of acute endotoxemia on hepatocyte nitric oxide production and functional activity. Treatment of rats with 5 mg/kg of lipopolysaccharide (LPS), which induces acute endotoxemia, caused an increase in nitric oxide production in the liver, as measured by electron paramagnetic spin trapping, which was evident within 6 hours. This was associated with expression of inducible nitric oxide synthase (iNOS) messenger (m) RNA in hepatocytes and in sinusoidal cells throughout the liver lobule. Acute endotoxemia also caused alterations in hepatic structure, including hypertrophy, vacuolization, and chromosomal emargination, however these changes were not apparent for 24 to 48 hours. Hepatocytes isolated from endotoxemic rats released increased amounts of nitric oxide, measured by nitrite production, in response to interferon gamma (gamma-IFN) alone or in combination with LPS, tumor necrosis factor alpha, macrophage-colony stimulating factor, granulocyte/macrophage-colony stimulating factor, or hepatocyte growth factor. These results show that hepatocytes are sensitized by acute endotoxemia to respond to inflammatory mediators and growth factors. Increased nitrite production by hepatocytes was due to increased expression of iNOS mRNA and protein and was correlated with the time following induction of acute endotoxemia. Thus, cells isolated 48 hours after induction of acute endotoxemia released significantly more nitrite than cells recovered after 6 hours, a response that was not due to alterations in hepatocyte viability. Hepatocytes isolated from endotoxemic rats also exhibited a marked increase in proliferative capacity when compared with cells from control rats. Nitric oxide production by hepatocytes in vitro was associated with inhibition of cell growth and protein synthesis, which was reversed by the nitric oxide synthase inhibitor, NG-monomethyl-l-arginine (L-NMMA). Agarose gel electrophoresis showed extensive cytoplasmic DNA fragmentation in hepatocytes treated with LPS and gamma-IFN, a characteristic of apoptosis, which was also reversed by L-NMMA. These results, together with our findings that treatment of rats with an inhibitor of nitric oxide synthase partially reversed the structural alterations in the liver associated with acute endotoxemia suggest that nitric oxide may contribute to the pathophysiologic response to this bacterially derived toxin.

The effects of colony stimulating factors on human monocyte cell function

We used a panel of functional assays to compare directly the pattern and potency of GM-CSF and M-CSF on monocyte activity associated with cell-mediated immune defense. GM-CSF and M-CSF were found to be equivalent both in their capacity to stimulate human monocyte functions in vitro and in their pattern of monocyte activation. The two CSFs were effective in inducing monocyte chemotaxis towards either fMLP or LTB4 at equivalent concentrations across a panel of donors. GM-CSF and M-CSF demonstrated equipotency in the induction of monocyte phagocytosis of heat-killed baker's yeast and in the regulation of the hexose-monophosphate shunt (NBT reduction). Both were also found to be equivalent in preventing steroid (dexamethasone)-induced suppression of monocyte anti-bacterial (Candida albicans) and anti-fungal (Staphylococcus aureus) phagocytic capacities. GM-CSF was somewhat more effective than M-CSF in stimulating monocyte C. albicans killing at a lower E:T ratio.

Immunoaffinity measurement of recombinant granulocyte colony stimulating factor in patients with chemotherapy-induced neutropenia

A high-performance immunoaffinity chromatographic technique has been developed for the measurement of recombinant human granulocyte colony stimulating factor in human patients receiving this agent, following neutropenia, arising from cancer chemotherapy. The technique employs a short, biocompatible polymer column packed with minute, antibody-coated glass beads. This system was applied to the analysis of recombinant human granulocyte colony stimulating factor in three different human body fluids. A reasonable degree of correlation was achieved when comparing the immunoaffinity technique to a conventional immunoassay, although the immunoaffinity technique displayed greater specificity.

Epirubicin. Clinical pharmacology and dose-effect relationship

The pharmacokinetic properties of epirubicin are characterised by a triphasic plasma clearance, with half-lives for the initial (alpha), intermediate (beta) and terminal (gamma) elimination phases of approximately 3 minutes, 1 hour and 30 hours, respectively. These values are similar to or slightly shorter than the corresponding half-lives of doxorubicin. The total plasma clearance of epirubicin is approximately 50 L/h/m2, which is almost 2-fold higher than that of doxorubicin. This difference is mainly due to the relatively high volume of distribution of epirubicin, and the unique glucuronidation metabolic pathway of epirubicin and epirubicinol, which is not available to doxorubicin or doxorubicinol. Glucuronide metabolites of epirubicin and epirubicinol are not active per se, but could divert epirubicin from free radical formation, which may induce cardiotoxic effects. This may explain, at least in part, the lower cardiotoxicity of this new anthracycline relative to that of the parent compound. There is a linear relationship between the dose administered and area under the plasma concentration-time curve (AUC) values of both unchanged drug and metabolites, so that the total plasma clearance of epirubicin is constant with epirubicin doses ranging from 40 to 140 mg/m2. No variation in total plasma clearance as a function of age in the range of 31 to 74 years has been observed, and this parameter is unaffected by subsequent courses of treatment. Hepatic dysfunction causes an increase in the terminal elimination half-life of epirubicin, which is well correlated with serum bilirubin levels and which necessitates a reduction in epirubicin dosage. Epirubicin is responsible for a dose-dependent neutropenia, which is clearly related to drug exposure as established in pharmacodynamic studies. The maximum tolerated dose (MTD) of epirubicin was first established to be approximately 90 mg/m2 but this was re-examined recently and is now deemed to be approximately 150 mg/m2, which is about 2-fold higher than the MTD of doxorubicin. Cumulative cardiac toxicity occurs for both epirubicin and doxorubicin, but the dose ratio for equal risk is about 1.8 in favour of epirubicin (500 to 550 mg/m2 for doxorubicin vs 900 to 1000 mg/m2 for epirubicin). Consequently, there is not a higher risk of developing cardiotoxicity after administration of high dose epirubicin, since this adverse effect is associated with total cumulative anthracycline dose. In several controlled trials, epirubicin exhibited the same anticancer activity as doxorubicin when administered at equimolar doses to patients with advanced breast cancer.(ABSTRACT TRUNCATED AT 400 WORDS)